Recovery of copper and cobalt in the comparative flotation of a sulfide ore using xanthate and dithiophosphate collectors (original) (raw)

2019, IJEAS

 Abstract-Copper and cobalt are two major metals used in industry. They play a role in widely many domains like that electricity, chemistry and electrochemistry. They are contained into several minerals like chalcopyrite, carrolite, chalcocite, etc. associated to pyrite. The froth flotation and behaviors of chalcocite and carrolite were investigated through many flotation tests in order to recovery copper and cobalt. This paper investigates the effect of potassium amyl xanthate (PAX) and sodium dibutyl dithiophosphate (DANA) performance on both copper and cobalt recovery in single roughing flotation. The effect of pH on the flotation is proposed. Some parameters were kept constant such as particle size d80=75 μm, pulp density 10% solids, impeller speed 1300 rpm, and PAX doses of DANA (105 g/t per each) as collectors, dose of DF250 (5 drops) as frother, dose of Na 2 SiO 3 (200 g/t) as dispersant and depressant. Only the pulp pH was varied from the natural pH to 11, using Ca(OH) 2 as regulator. According to results, PAX (105 g/t) was found as the best collector for recovery of copper both at natural pH and pH=11. At natural pH, the concentrate was found at 16.1% copper recovery with a yield of 99.63%. At pH=11, the concentrate was found at 16.1% copper recovery with a yield of 99.05%. For the recovery of cobalt, DANA (105 g/t) was found better as the collector at natural pH producing a concentrate at 0.51% cobalt recovery yield of 76.48%. At pH=11, PAX (105 g/t) was found better as the collector. The concentrate was found at 0.91% cobalt with a recovery yield of 85.13%.

A review of the beneficiation of copper-cobalt-bearing minerals in the Democratic Republic of Congo

A review of the beneficiation of copper-cobalt-bearing minerals in theDemocratic Republic of Congo, 2019

Copper and cobalt (Cu-Co) are strategic metals for the Democratic Republic of Congo (DRC), and nearly 20% of the country's GDP is supported by their exports. At present, the country classifies itself as the leading copper producer in Africa with an output in the region of a million tonnes and possesses nearly 60% of the world's reserves of Co; a metal exclusively exported in the form of salts or semi-finished products. Concentrators play a very important role in the growth of Cu-Co metal production, which is needed in order to meet rapidly growing global demand and to increase government revenues through mining royalties. This article reviews the major process flow sheets and reagent suites in practice at concentrators operated in the DRC for the beneficiation of Cu-Co values from various ore types. The comprehensive compilation of pertinent laboratory and industrial data is intended to provide practising specialists, metallurgists, and academics conducting research on Congolese Cu-Co ores with a single well-detailed reference source. Emphasis is placed on froth flotation as the major technique for the beneficiation of Cu-Co minerals.

Sulfide Mineral Flotation

Froth flotation was developed at the Broken Hill mine, Australia, a century ago with the flo-tation of the common sulfide mineral, sphalerite. With this development, billions of tons of worthless rock containing a variety of valuable metals became ore. Anchoring this revolutionary development was the later introduction of xanthate as a collector for sulfide minerals. Probably more than any other aspect, xanthate entrenched froth flotation's role in the utilization of the world's natural mineral resources. Sulfide minerals are the largest of the groups of minerals floated. Today, more than a billion tons of sulfide ores are concentrated annually throughout the world with this technology. As a group, these minerals possess a number of unusual properties that are utilized in their flotation concentration. They are conductors of electrons, they develop a potential when placed into a solution, their surfaces are readily oxidized by dissolved oxygen, and their contained metals form insoluble collector compounds with short-chained collectors. These properties enable categorization of sulfide minerals. Chander (1985) has proposed categorizing them into two classes: reversible and irreversible (passivated) sulfides. In general, the properties of reversible sulfide systems can be predicted from thermodynamic considerations, and their potential response in aqueous solution can often be predicted by the Nernst equation. Minerals that fall into this category are galena, chalcocite, and sphalerite. In contrast, irreversible sulfides are often covered with products of oxidation-reduction reaction, and the properties of these systems require close scrutiny of time effects and the history of the mineral surface. Pyrite, chalcopyrite, and arsenopyrite are examples of minerals in this system. Some sulfide minerals (e.g., molybdenite) can be floated without collector addition in the presence of air, while others can be floated in the absence of a collector under conditions in which mild oxidation of the contained sulfide to elemental sulfur or polysulfide occurs. Each of these categories is discussed separately in this chapter.

Sulphide mineral flotation : a new insight into oxidation mechanisms

2013

Formation of hydrogen peroxide (H2O2), an oxidizing agent stronger than oxygen, by sulphide minerals during grinding was investigated. It was found that pyrite (FeS2), chalcopyrite (CuFeS2), sphalerite ((Zn,Fe)S), and galena (PbS), which are the most abundant sulphide minerals on Earth, generated H2O2 in pulp liquid during wet grinding in the presence or devoid of dissolved oxygen in water and also when the freshly ground solids are placed in water immediately after dry grinding. Pyrite generated more H2O2 than other sulphide minerals and the order of H2O2 production by the minerals found to be pyrite > chalcopyrite > sphalerite > galena. The pH of water influenced the extent of hydrogen peroxide formation where higher amounts of H2O2 are produced at highly acidic pH. The amount of H2O2 formed also increased with increasing sulphide mineral loading and grinding time due to increased surface area and its interaction with water. The sulphide surfaces are highly catalytically active due to surface defect sites and unsaturation because of broken bonds and capable of breaking down the water molecule leading to hydroxyl free radicals. Type of grinding medium on formation of hydrogen peroxide by pyrite revealed that the mild steel produced more H2O2 than stainless steel grinding medium, where Fe2+ and/or Fe3+ ions played a key role in producing higher amounts of H2O2. Furthermore, the effect of mixed sulphide minerals, i.e., pyrite–chalcopyrite, pyrite–galena, chalcopyrite–galena and sphalerite–pyrite, sphalerite–chalcopyrite and sphalerite–galena on the formation of H2O2 showed increasing H2O2 formation with increasing pyrite fraction in chalcopyrite–pyrite composition. In pyrite–sphalerite, chalcopyrite–sphalerite or galena–sphalerite mixed compositions, the increase in pyrite or chalcopyrite proportion, the concentration of H2O2 increased but with increase in galena proportion, the concentration of H2O2 decreased. Increasing pyrite proportion in pyrite–galena mixture, the concentration of H2O2 increased and also in the mixture of chalcopyrite–galena, the concentration of H2O2 increased with increasing chalcopyrite fraction. The results of H2O2 formation in pulp liquid of sulphide minerals and mixed minerals at different experimental conditions have been explained by Eh–pH diagrams of these minerals and the existence of free metal ions that are equally responsible for H2O2 formation besides surfaces catalytic activity. The results also corroborate the amount of H2O2 production with the rest potential of the sulphide minerals; higher is the rest potential more is the formation of H2O2. Most likely H2O2 is answerable for the oxidation of sulphide minerals and dissolution of non-ferrous metal sulphides in the presence of ferrous sulphide besides the galvanic interactions. This study highlights the necessity of revisiting into the electrochemical and/or galvanic interactions between the grinding medium and sulphide minerals, and interaction mechanisms between pyrite and other sulphide minerals in terms of their flotation behaviour in the context of inevitable H2O2 existence in the pulp liquid.

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