Agglomeration experiment of secondary copper sulfide ore

The presence of a large amount of fine particles and muddy ore during the heap leaching process leads the occurrence of low leaching rate. Herein, agglomeration experiments using low-grade secondary copper sulfide ore were conducted to enhance the poor heap permeability and low leaching rate caused by the presence of a large amount of fine particles during the heap leaching process. The optimum binder, agglomeration technology, and agglomeration method were selected after investigating the bonding effects of different binders on mineral particles. The effect of single factor, including the binder mass fraction, acid quality, and bulk of water spraying on agglomeration experiments were conducted before the orthogonal experiment. The key factors that have a considerable effect on agglomeration were identified through the orthogonal experiment. According to the experimental results, the order of bonding effect of different granulation binders is as follows: SFS-2 > SFS-3 > cement > hemihydrate gypsum > SFS-1 > SFS-0 > sodium silicate > cationic polyacrylamide. The effect of agglomeration is the best when SFS-2 is selected as a binder, the acid quality is measured as 25 kg·t^-1, and the mass fraction of spraying water is 30% during the agglomeration process. The wet strength and compressive strength reaches up to 94.62% and 417.44 N, respectively, after drying. The acid leaching time of agglomerations is maintained for more than 25 d, during which the shape of agglomerations remains unchanged and is without obvious fracture. According to the orthogonal experiment, the factors affecting the agglomeration in the descending order are as follows: binder mass fraction, acid quality, and bulk of water spraying. The bacterial inoculation experiment in the presence of binder was conducted, but it shows no considerable effect of binder on the bacterial community. The bacterial number of experiment in the presence of binder reaches 8.79×10⁷ mL^-1, while that in the absence of binder is 8.86×10⁷ mL^-1. The leaching experiments results show that the copper leaching rate increases by 12.74% after agglomeration because agglomeration increases the porosity between the minerals and improves the contact between leaching solution and minerals.