Adsorption Characteristics Of Metal Ions On Mineral Surface In Malachite Sulfide Flotation System And Its Effect On Flotation

Copper is widely used in industrial production and plays an important role in national economic development.Copper ores are mainly composed of copper sulfides and oxides,with the oxide deposits evolving from the long-term oxidation of exposed copper sulfide layers.As the high demand for copper ore in industrial production outstrips supply,the efficient recovery and utilization of copper oxide ore has become an effective source of supplementing copper resources.In the process of mineral flotation,there are many kinds of metal ions in the pulp,mainly from artificially added flotation reagents,dissolution of associated metal minerals in the crushing and grinding process,the consumption of grinding medium,flotation water,et.In flotation production,enhancing the activation effects of metal ions in the pulp on the mineral sulfidization-flotation,or avoiding the negative impacts,can effectively improve the flotation recovery rate and provide a theoretical basis for the efficient separation of oxidized copper ore.In this paper,with malachite(Cu(OH)₂CO₃)as the research object,the adsorption characteristics of Pb²⁺,Cu²⁺,Fe²⁺,and Fe³⁺ions at the mineral interface and the mechanism of sulfidization-flotation were studied.Flotation tests,contact angle tests,zeta potential and adsorption experiments,solution species calculations,inductively coupled plasma optical emission spectroscopy,X-ray photoelectron spectroscopy,and time-of-flight secondary ion mass spectrometry were performed to systematically study the adsorption characteristics of metal ions on malachite.The effects of this adsorption on malachite and on the surface sulfidization,collector adsorption,and floatability in multiple sulfidization systems were studied.Pb²⁺,Cu²⁺,Fe²⁺,and Fe³⁺ions could all be adsorbed on the malachite surface at natural p H levels.The Pb²⁺ions in the solution combine with oxygen sites on the malachite surface to form Pb–O components on the mineral.At the same time,a dehydration reaction occurs between the Pb(OH)⁺and the Cu–OH components on the surface,increasing the local reaction activity.After adding appropriate amounts of Cu²⁺ions to the solution,these ions combine with oxygen sites on the mineral surface to form Cu–O components,increasing the Cu component content and increasing the surface reaction activity.When large amounts of Cu²⁺ions are added,more Cu–OH components form on the surface.This increases the content of OH components,which is not conducive to the subsequent sulfidization-flotation of malachite.Fe²⁺and Fe³⁺ions added to the solution are adsorbed onto the mineral's surface by forming metal-ion hydroxyl components(Fe OOH),which reduce the mineral's surface activity.Adding Pb²⁺,Cu²⁺,and Fe³⁺ions before and after malachite sulfidization can increase the content of surface sulfide components.Compared with the condition of direct sulfidization,adding proper concentrations of Pb²⁺and Cu²⁺ions before sulfidization causes Pb–O and Cu–O components to cover the mineral surface.This increases the number of active surface sites,which increases the adsorption of Pb–S and Cu–S components.Pb²⁺and Cu²⁺ions added after sulfidization can react with and improve the activity of the mineral surface,with the additional Pb–S/Cu–S components promoting the adsorption of sulfur in the solution onto the mineral surface.Adding Pb²⁺and Cu²⁺ions into the malachite sulfidization-flotation system thus increases the content of Cu–S components formed on the mineral's surface,which shows that the addition of Pb²⁺and Cu²⁺ions can promote the sulfidization of malachite.Adding high concentrations of Cu²⁺ions increases the proportion of Cu–OH components on the mineral surface,which decreases the proportion of Cu–S components.The added flotation reagent is thus consumed,which is not conducive to the sulfidization-flotation of malachite.Adding Fe²⁺ions before or after malachite sulfidization decreases the proportion of Cu–S components on the mineral surface,negatively impacting the sulfidization,with the Fe–OH components also reducing the local reaction activity.The addition of Fe²⁺ions is therefore not conducive to the sulfidization-flotation of malachite.Fe³⁺ions added before or after sulfidization form Fe OOH components on the surface.During sulfidization,this Fe reacts with sulfur to form Fe–S components that can be oxidized to form Fe–SO₄ components,which reduce the reactivity of the mineral's surface and depress the formation of Cu–S components.These Fe–S and Fe–SO_n components in the solution are then adsorbed onto the mineral surface,which reduces the sulfidization activity at the surface and reduces the content of Cu–S components.The addition of Fe³⁺ions is therefore not conducive to the sulfidization-flotation of malachite.The addition of Pb²⁺ions and an appropriate concentration of Cu²⁺ions to the pulp solution can improve the hydrophobicity and flotation recovery of malachite.From an original recovery rate of 68.54%without adions,the recovery of pure malachite increased from to 94.22%and 89.83%when Pb²⁺ions were added before and after sulfidization,respectively.After verifying the actual ore through flotation closed-circuit tests,it was found that the recovery of copper oxides was increased by about 5%.Similarly,the flotation recovery rates of pure malachite minerals increased to 75.93%and 80.21%by adding proper concentrations of Cu²⁺ions before and after sulfidization,respectively.The actual ore flotation verification test shows that the addition of Cu²⁺ions improved the recovery of copper oxides.By contrast,adding Fe²⁺ions before and after sulfidization decreased the flotation recovery of malachite by 13.81%and 20.42%,respectively.However,adding Fe³⁺ions caused the greatest drop,reducing the flotation recovery rates by 55.31%and 53.34%before and after sulfidization,respectively.The flotation test of actual minerals also shows that the addition of Fe³⁺ions reduced the flotation recovery of oxidized copper minerals.This systematic investigation has demonstrated the importance of considering the interactions between adsorbed metal ions and sulfidizing reagents.This is of great significance to determining the effect of adsorbed metal ions on the sulfidization of malachite,ascertaining the hydrophilic/hydrophobic state of the sulfidized mineral surface,and setting up the hydrophobic regulation methods of copper oxide minerals.