Full Answer
What is the best reagent for cobalt recovery from copper raffinate?
Organophosphorus acids were considered to be the most promising family of reagents for cobalt recovery from the copper extraction raffinate. Commercially available organophosphorus acids include phosphoric, phosphonic, and phosphinic acids.
What is the best way to reduce cobalt II without precipitating?
The efficiency of cobalt reduction increased with increasing concentration of NaOH in the reducing solution, the best reduction efficiency without the precipitation of cobalt hydroxide being 1 mole of sodium borohydride to reduce 1 mole of cobalt(II).
How do you extract cobalt from copper?
selective cobalt extraction from copper solvent extraction raffinate with a phosphinic acid extractant, and electrowinning of cobalt from a recirculating weak acid strip liquor. Figure 1 is a conceptual flow diagram of the process investigated on a bench scale.
Can precipitation-solvent extraction be used to extract cobalt and copper from cobaltite?
This laboratory-scale investigation demonstrated the feasibility of using a combination precipitation-solvent extraction approach to the recovery of cobalt, copper, and possibly nickel from a cobaltite flotation concentrate.
At what pH do metals precipitate?
pH 6 to 9The pH required to precipitate most metals from water ranges from pH 6 to 9 (except ferric iron which precipitates at about pH 3.5). The types and amounts of metals in the water therefore heavily influence the selection of an AMD treatment system.
Which reagent is used for precipitation of Cu?
16.2. 2 Chemical PrecipitationRadionuclideProcess reagentpHRuCopper + ferrous hydroxides8.5Cobalt sulphide1–8.5Sodium borohydride8.5CsFerrocyanide6–1022 more rows
How do you precipitate cobalt?
With sodium hydroxide solution and hydrogen peroxide You get the variably colored precipitate of the cobalt(II) hydroxide complex when you add the sodium hydroxide solution. Addition of hydrogen peroxide produces lots of bubbles of oxygen and a dark chocolate brown precipitate.
What does cobalt react with?
Cobalt is one of the three metals that are ferromagnetic at room temperature. It dissolves slowly in dilute mineral acids, does not combine directly with either hydrogen or nitrogen, but will combine, on heating, with carbon, phosphorus, or sulfur.
What happens when you add sodium hydroxide solution to copper II ions?
The reaction of hexaaquacopper(II) ions with hydroxide ions Hydroxide ions (from, say, sodium hydroxide solution) remove hydrogen ions from the water ligands attached to the copper ion. Once a hydrogen ion has been removed from two of the water molecules, you are left with a complex with no charge - a neutral complex.
What happens when copper reacts with sodium hydroxide?
Copper(ll) ions Cu2+ react with sodium hydroxide to form blue coloured precipitates of copper(ll) hydroxide as: Cu2++2OH−→Cu(OH)2(s)
Is cobalt an acid or base?
COBALT CHLORIDE acts as a weakly acidic inorganic salt, which is soluble in water. The resulting solutions contain moderate concentrations of hydrogen ions and have pH's of less than 7.0. They react as acids to neutralize bases.
What happens when sodium hydroxide solution is added to cobalt II chloride solution?
Here, sodium hydroxide (NaOH) is added to cobalt(II) chloride (CoCl2). The result is a red solution and a blue-green precipitate.
Why does the cobalt solution turn brown upon addition of sodium hydroxide?
This basic salt is insoluble in excess sodium hydroxide, but is soluble in acids. When heated, the basic salt hydrolyzes to form Co(OH)2. Cobalt(II) hydroxide is slowly oxidized by atmospheric oxygen to form brown Co(OH)3.
Does cobalt react with HCL?
Cobalt gives cobalt(II) chloride by dissolving in dilute hydrochloric acid [4]. It is insoluble because it acquires passivity in concentrated nitrate and sulphuric acid [6]. Another oxidation number of cobalt is +3.
Is cobalt a hydroxide?
) is a pink solid insoluble in water. Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). ), which incorporates other anions in its molecular structure.
Is cobalt reactive or inert?
Chemical properties Cobalt is a moderately reactive element. It combines slowly with oxygen in the air, but does not catch fire and burn unless it is in a powder form. It reacts with most acids to produce hydrogen gas. It does not react with water at room temperatures.
What is cobalt extraction?
Cobalt extraction refers to the techniques used to extract cobalt from its ores and other compound ores. Several methods exist for the separation of cobalt from copper and nickel. They depend on the concentration of cobalt and the exact composition of the used ore .
How to treat nickel cobalt lateritic ores?
Nickel-cobalt lateritic ores can be treated by either hydrometallurgical processes or pyrometallurgical processes, such as matte or ferro nickel smelting, which require the entire ore to be melted and the metal values to be separated from the residual components of the ore. The hydrometallurgical process for laterite ore can use sulfuric acid or ammonia leach solutions.
How is cobalt smelted?
The ore is comminuted and the cobalt rich oxides are separated by froth flotation. The cobalt-bearing concentrate is then mixed with lime and coal, and then melted in a reducing atmosphere. Iron and lighter impurities float to the surface as solid dross or are expelled from the melt as gas. The remaining liquid is composed of a heavier copper smelt containing approximately 5% cobalt that is processed for its copper and a lighter slag that is approximately 40% cobalt that is further refined by hydrometallurgical and electrolytic processing. Concentrations of cobalt oxide (Co 3 O 4) may also be reduced by the aluminothermic reaction or with carbon in a blast furnace.
What is the treatment for roasted ores?
The roasted ores can be treated with hydrochloric acid and chlorine or with sulfuric acid to give a leach solution that can be purified by hydrometallurgical methods and from which cobalt can be recovered by electro refining or by carbonate precipitation.
How to treat nickel sulfide?
Nickel sulfide concentrates can be treated by either roasting or flash smelting to produce matte from which nickel and cobalt can be recovered hydrometallurgically, or they may be treated by an ammonia solution pressure leach. The residue is removed.
How is copper precipitated?
By boiling away the ammonia; copper is precipitated as a sulfide and sent to a smelter. Hydrogen sulfide is added to the autoclave to remove nickel sulfide and copper sulfide which is fed back to the leaching process. Air is then passed through the solution in the autoclave for oxyhydrolysis.
How is iron removed from a leach solution?
Iron and aluminum are removed from the leach solution by the addition of lime, and copper is electrowon on copper cathodes. A part of the spent electrolyte enters the cobalt recovery circuit and is purified by the removal of iron, copper, nickel, and zinc prior to the precipitation of cobalt as its hydroxide.
Procedure
Mix nickel nitrate solution with sodium carbonate solution to form a green ppt. of nickel carbonate.
Discussion
Carbonate salts are insoluble with the exception of those containing alkali metal ions and ammonium ions.
How to maintain copper sulfate bath?
Troubleshooting, purification. Acid copper sulfate baths are easy to maintain. Use quantitative analysis to control copper, sulfur ic acid and chloride. Add proprietary addition agents, which control brightness, ductility, and leveling, on the basis of amp-hr. You can also regulate their addition by using Hull cells and a copper analysis.
What is acid copper bath?
Acid copper baths are simple formulations, containing copper ions, additives and either sulfate or fluoborate ions along with the corresponding acids. Because of their acidity, they cannot be plated directly onto active metals, such as zinc die castings and steel, for they will produce non-adhering immersion deposits.
What is the pH of cyanide copper?
A typical bath formulation contains 11g/L of copper metal. The pH is around 9.0, while cyanide copper solutions have a pH of at least 11.0. The anode-to-cathode ratio is 2:1, with the same anodes used in cyanide copper solutions.
What is cyanide copper used for?
A cyanide copper solution can be used in either rack or barrel plating. The processes can be generally classified as low-efficiency or “strike” processes, medium-efficiency “Rochelle” processes and high-metal, high-efficiency or “high-speed” processes.
Why is copper used as an undercoat?
There are several reasons for this: Copper is an excellent undercoat for subsequent deposits, since it's a good metal to cover substrate defects that can accelerate corrosion.
What is Rochelle salt bath?
The Rochelle salt bath is often used for similar purposes. But, it may also be used to provide thicker deposits than can be obtained with cyanide strike baths. The high-efficiency formulation, with its higher temperature and copper concentration, plates faster and can produce thicker deposits.
What is copper strike?
The copper strike serves only as a protective layer for further plating, typically with copper or nickel. It also improves adhesion and, in some cases, acts as “insurance” in the preplate cycle to obtain adhesion because cyanide can function as a cleaner/activator.