How do you process chromite?
When chromite and lime are melted in an open electric-arc furnace and then contacted with ferrochrome silicon, a low-carbon (0.05 percent) ferrochromium can be obtained. In an alternate process, high-carbon ferrochromium is oxidized and then blended with additional high-carbon ferrochromium.
What method is used to mine chromite?
Mining of chromite is carried out by open-pit and underground mining. Whereas open-pit mining is generally applied to podiform deposits, underground mining is applied to stratiform deposits.
How ferrochrome is produced?
Ferrochrome is manufactured by conducting carbothermic reduction of iron magnesium chromium oxide under high temperatures. Iron-chromium alloy is produced by the reduction of Chromium Ore by the application of coal and coke. This reduction process requires heat which comes from the electric arc of the furnace.
How is chromite separated?
The separation is carried out using a magnetic separator as the chromite sand can be weakly magnetized. Permanently magnetic, high intensity separators are used in combination with cleaning and dust-removal devices. The magnetic separator has two consecutive separation steps.
What process is used in reduction of chromium oxide into chromium metal?
Chromium metal by the reduction of Cr2O3. This is obtained by aerial oxidation of chromite in molten alkali to give sodium chromate, Na2CrO4, which is leached out with water, precipitated and then reduced to the Cr(III) oxide by carbon.
How do you dissolve chromium?
Chromium(III) oxide (Cr2O3) can be reactively dissolved with sulfuric acid (~85 wt%; H2SO4/Cr2O3 ≥ 6 wt/wt) mixed with perchloric acid (HClO4/Cr2O3 ≈ ½ wt/wt) by ~175 ºC (≤ 4h; under reflux).
What type of concentration or dressing is applied for chromite ore?
Chromite (FeO. Cr2O3) is magnetic ore. So the concentration of chromite (FeO. Cr2O3) is done by magnetic separation because it easily get separated due to magnetic property.
What is the ferrochrome?
Ferrochrome, or Ferrochromium (FeCr) is a type of ferroalloy, that is, an alloy between chromium and iron, generally containing 50% to 70% chromium and is used in the production of stainless steel, special steel and castings.
What is ferrochrome slag?
Ferrochrome slag is a waste material obtained from the manufacturing of high carbon ferrochromium alloy. This slag is formed as a liquid at 1700 °C and its main components are SiO2, Al2O3 and MgO. Additionally it consists of chrome, ferrous/ferric oxides and CaO.
How is chromite extracted from its ore?
Chromium is generally extracted from its ores by oxidation in the form of chromate, in which state its valence is six. The product of this reaction is then treated to extract the chromate.
How is chromium extracted from chromite?
Can chromium react with water?
Elementary chromium does not react with water at room temperature. Many chromium compounds are relatively water insoluble. Chromium (III) compounds are water insoluble because these are largely bound to floating particles in water. Chromium (III) oxide and chromium (III) hydroxide are the only water soluble compounds.
Does chromium dissolve in nitric acid?
Chromium metal is not dissolved by nitric acid, HNO3 but is passivated instead.
What is the concentration process for reduction of ores?
Ore concentration can be accomplished through a variety of methods, including hydraulic washing, magnetic separation, froth flotation, and leaching.
Can chromite be concentrated by magnetic separation?
What is the use of ferroalloys?
Ferroalloys impart distinctive qualities to steel and cast iron and serve important functions during iron and steel production cycles. The principal ferroalloys are those of chromium, manganese, and silicon. Chromium provides corrosion resistance to stainless steels.
What is high carbon ferro chrome?
High carbon ferrochrome represents a group of alloys with a chromium content typically between 60% and 70% and a carbon content typically between 4% and 6%. To meet this specification the alloy requires a chromite ore with a high Cr/Fe ratio (>2).
Where is chromium extracted from?
Chromium is chiefly obtained from the mineral chromite. It is mined in South Africa, Kazakhstan, India, Albania, and Turkey.
What happens when chromium is heated?
Chromium is a lustrous, brittle, hard metal. Its colour is silver-gray and it can be highly polished. It does not tarnish in air, when heated it borns and forms the green chromic oxide. Chromium is unstable in oxygen, it immediately produces a thin oxide layer that is impermeable to oxygen and protects the metal below.
Does HCL dissolve chromium?
Reaction of chromium with acids Chromium metal dissolves in dilute hydrochloric acid to form solutions containing the aquated Cr(II) ion together with hydrogen gas, H2. In practice, the Cr(II) is present as the complex ion [Cr(OH2)6]2+.
How do you precipitate chromium?
Boiling the solution causes the chromium(III) hydroxide to reprecipitate. Sodium Hydroxide: Strong bases such as NaOH also precipitate Cr(OH)3, but the precipitate dissolves in excess hydroxide.
What are the 4 methods for concentrating ores?
Which method is used for concentration of ore?
Froth Flotation Process Another method of concentration of ores is the Froth Flotation Method. This is the process for concentration of primarily sulphide ores. It has the advantage over gravity separation because it can collect even the extremely fine particles of minerals.
What are the steps involved in the reduction of chromite?
In the early stages of the reduction, stoichiometric and excess carbon. In the later stages, reduction reactions progressed by solved C in the alloy. As there was didn’t affect the reduction degree. Metallographic analysis. According to the SEM micrographs of the chromite spinel by nucleation of iron (Figs. 3 and 4).
What is the pre-reduction of chromite with carbon?
Ore, coke and fluxes are mixed and reacted in an arc furnace for a smelting process of ferrochromium. In addition to this process, pre-reduction of chromite ore with carbon is an important industrial process. In all these processes, the mechanism and kinetics of reduction of chromite with carbon play an important role.
Why does chromite have a lower ratio of Cr/Fe than oxide?
The different reaction mechanism of the chromite with a lower ratio of Cr/Fe was due to the meltdown of the alloy layer from the oxide particles. Experimental studies were conducted on the effect of a combination of lime and silica fluxes on the carbothermic reduction of chromite.
What are the effects of the activation procedure on chromite?
The activation procedure led to amorphisation and structural disordering in chromite, and accelerated the degree of reduction and metallisation in the mixture of chromite and graphite.