Flotation Separation of Covellite and Enargite via Oxidation Treatment

The flotation separation of enargite from copper sulfide minerals is difficult owing to the similar floatability and reagent adsorption characteristics of these minerals. In this study, the effect of oxidation treatment using NaClO flow with FeCl3 on the flotation separation of covellite and enargite was systematically investigated. Micro-flotation tests and contact angle measurements indicated that the addition of NaClO and FeCl3 increased the hydrophobicity difference between covellite and enargite. The bench-scale flotation test results show that the bulk copper concentrate could be separated into two products: a low-arsenic-containing (0.46%) and a high-arsenic-containing (5.18%) copper concentrate. X-ray photoelectron spectroscopy and scanning electron microscopy revealed that the oxidization treatment of NaClO caused the accumulation of oxides on the covellite surface, but not on the enargite surface. The varying precipitation of ferric hydroxide on the surfaces of covellite and enargite further exacerbated the difference in the hydrophilicity of these minerals. Thus, a possible method for separating enargite from covellite was obtained through oxidation treatment using NaClO and FeCl3

Effect of the foaming performance of ammonium dibutyl dithiophosphate on the flotation of slime-containing copper sulfide ore

The use of ammonium dibutyl dithiophosphate (ADD) as a collector in the flotation of slimecontaining copper sulfide ore typically produces a sticky froth, which results in poor flotation. The mechanism and effects of copper sulfide ore flotation in synergistic systems comprising ADD and terpenic oil reagents have been systematically investigated to solve this problem. A high ratio of ADD to terpenic oil is not conducive to the flotation of fine-grained copper sulfide ores; however, adjusting this ratio may improve floatation by reducing the effect of the slime. Lowering the ratio from 5:1 to 1:1 increased the copper grade from 17.7% to 20.8%, while the recovery was largely unchanged. Notably, adjusting this ratio also reduced the cost of the flotation reagent. To study the mechanism by which the ADD–to–terpenic oil ratio affects the foam performance, the froth stability tests of the gas–liquid twophase and gas–liquid–solid three-phase systems were performed. Reducing the proportion of ADD reduced the froth water content and weakened the ability of the froth to collect gangue by adsorbtion with copper ions; this reduced gangue entrainment and maximized recovery and product quality

Strengthening Sulfidation Flotation of Hemimorphite via Pretreatment with Pb2+

The conventional sulfidation-xanthate flotation process that consists of sulfidization with sodium sulfide, activation by heavy-metal ions, and collection with xanthate is not sufficiently efficient for treating hemimorphite, and the dosages of the sulfurizing reagent and metal ions are large. In this study, the sulfidation flotation (Pb2+ + Na2S + Pb2+ + xanthate) of hemimorphite was strengthened by pretreating with Pb2+ before sulfidation. Microflotation test results indicated that the recovery of hemimorphite increased by 5–10% after pretreatment with Pb2+. The comprehensive results of adsorption experiments, scanning electron microscopy–energy-dispersive X-ray spectroscopy, atomic force microscopy, and X-ray photoelectron spectroscopy indicated that a large amount of Pb2+ was adsorbed on the hemimorphite surface and entered the lattice, forming Zn(4−x)PbxSi2O7(OH)2·H2O. The newly formed component had an increased amount of surface sulfidation active sites and had the effect of induced crystallization, making the surface more effective for sulfidation. After the Pb2+ was added to the pulp, a large number of uniform and dense PbS species were formed on the hemimorphite surface, increasing the number of adsorption sites for xanthate and reducing the competitive adsorption of residual S2− on the xanthate

Growth behavior of iron grains during deep reduction of copper slag

The change in granularity of iron grains in copper slag during coal-based deep reduction was identified using optical microscopy and the Image J analysis software. The growth behavior of iron grains was investigated based on the Hillert dynamic model. The results indicate that the granularity and sphericity of iron grains are strongly affected by the reduction time and temperature during the deep reduction process. It is found that in isothermal condition, the growth rate of iron granularity increases with time exhibiting an S-shape characteristic. Meanwhile, in non-isothermal condition, the growth rate of iron granularity increases exponentially with temperature. When the reduction temperature is in the range of ~1423–1573 K and the reduction time was in the range of ~30–180 min, the grain growth kinetic parameters are calculated as follows: growth index n = 1.424 ± 0.07855, apparent activation energy Q = 116.17 kJ∙mol, and pre-exponential factor as 20,839.38

Effect of feed quantity on breakage degree of ore particles subjected to high voltage pulses

The effect of spatial arrangement of feed sample on the breakage degree of high voltage pulse breakage (HVPB) product was investigated by varying the number of feed particles discharged simultaneously inside a processing vessel. Two kinds of hard porphyry copper ores were treated using the commercial HVPB tester SELFRAG Lab and a custom-made unit respectively. The results indicate that, at given electrode gap and specific energy, the fineness (t10) of HVPB product increases with feed quantity, while the pre-weakening degree (CAb) of HVPB product decreases with feed quantity. A new index of equivalent product fineness (t10e), which reflects the combined effect of\ua0t10\ua0and\ua0CAb, is employed to represent the overall breakage degree of HVPB product. It is found that the value of\ua0t10e\ua0has a positive relation with the feed quantity of HVPB tests. The effect of feed quantity on ore behaviour in HVPB is attributed to the influence of particles bed volume on breakdown strength and the negative effect of water gap between ore particles and top electrode. Finally, it is recommended to take feed quantity into consideration in HVPB studies to obtain comparative testing results, and to select the most appropriate breakage degree indexes from\ua0t10,\ua0CAb\ua0and\ua0t10e\ua0according to research aim. Particularly, electrode gap just filled by feed particles is preferred to optimize the over breakage degree of ore particles

Effect of high voltage pulse treatment on the surface chemistry and floatability of chalcopyrite and pyrite

The effect of high voltage pulse (HVP) treatment on the surface chemistry and flotation behaviour of chalcopyrite and pyrite were investigated using single mineral. The results indicated that the effect of HVP treatment on pyrite was more significant than chalcopyrite, both in terms of size reduction degree and flotation behaviour. Despite the stronger resistance to mechanical breakage than chalcopyrite, the proportion of −0.053 mm product of pyrite was higher than chalcopyrite for 12.2 per cent in average after HVP treatment of different pulse numbers. The flotation recovery of chalcopyrite was only slightly reduced after HVP treatment of 130 pulse discharges. However, under the same test conditions, the flotation recovery of pyrite was reduced by 64.1 per cent in average. The flotation behaviour of the two single minerals were in agreement with their surface oxidation behaviour in HVP treatment. XPS analysis and EDTA extraction suggested that chalcopyrite surface had only partially oxidized by HVP treatment; whereas pyrite was deeply oxidized with a large amount of S element converted to be sulphate radicals. The relative permittivity of pyrite, chalcopyrite and water was 33.5, 78.1 and 80 respectively, which led to a ratio of electrical field strength inside pyrite, chalcopyrite and water theoretically being 2.39:1.02:1. As a result, pyrite particles had stronger capability to attract electrical breakdown channel than chalcopyrite, and subjected to more severe size reduction and surface oxidation under the same conditions. On the other hand, the slight surface oxidation of chalcopyrite particles was hypothesized to be caused by the active species (OH, H2O2, etc.) formed during pulse discharge

Analysis of magnetic particle agglomeration structure and interaction forces between magnetic particles

Chain-like and diamond-shaped magnetic particle agglomeration (MPA) commonly forming in a weak magnetic field are simulated based on the finite element method (FEM), and the effects of particle diameter, magnetic field strength, particle relative magnetic permeability, and particle number in magnetic particle chains (MPCs) and diamond-shaped MPA on the strength of MPA are analysed in detail. The results show that magnetic forces on the centre contact points (CCPs) of MPA are positively correlated with the particle diameter, magnetic field strength, particle relative magnetic permeability, and particle number. In addition, the forces on the CCPs of the MPCs (N=2) have a square relationship with the particle diameter and magnetic field strength and have a power relationship of 1.25 with the particle relative magnetic permeability. The forces on each contact point decrease slowly from the centre to both ends in the MPCs and then rapidly decrease to one value (approximately 0.779 times the forces on the CCPs). As for the diamond-shaped MPA, with the increase in the angle α between the magnetic field and axis of diamond-shaped MPA, the force magnitude of the particle entrained parallelly in the diamond-shaped MPA shows a trend of a “cosine curve” shape and the minimum value is 2109 times that of the entrained particle’s gravity. The angle θ between the direction of the force and the negative X-axis shows a trend of a “sine curve” shape. When α = 25º and 155º, the angle θ of the force on the entrained particle reaches an extreme value, that is, θ = 21.87º. Only if the angle θ reaches 30º can the particle entrained parallelly escape from the diamond-shaped MPA. Thus, the diamond-shaped MPA remains in a stable state and it is difficult to disperse MPA by changing the direction of the magnetic field