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Chromite Ore Roastingensearch1

Chrome chemicals are commercially produced by the alkali roasting of chromite ores with sodium carbonate. Results of tests conducted in a laboratory furnace indicated that the sodium carbonate reacted rapidly with part of the gangue material to form a metastable intermediate that later reacted further with the chromite. For the conditions used the recovery of water-soluble sodium chromate was able to be described empirically as yield tn with 0.24 T 8211 241.3 n 3.90 8211 3.12 10-3 T and t is the reaction time in hours.

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A Novel Reductive Alkali Roasting Of Chromite Ores For

A Novel Reductive Alkali Roasting Of Chromite Ores For

Chrome chemicals are commercially produced by the alkali roasting of chromite ores with sodium carbonate. Results of tests conducted in a laboratory furnace indicated that the sodium carbonate reacted rapidly with part of the gangue material to form a metastable intermediate that later reacted further with the chromite. For the conditions used the recovery of water-soluble sodium chromate was able to be described empirically as yield tn with 0.24 T 8211 241.3 n 3.90 8211 3.12 10-3 T and t is the reaction time in hours.

Alkali Roasting Of Chromite Ausimm

Alkali Roasting Of Chromite Ausimm

Description Chrome chemicals are commercially produced by the alkali roasting of chromite ores with sodium carbonate. Results of tests conducted in a laboratory furnace indicated that the sodium carbonate reacted rapidly with part of the gangue material to form a metastable intermediate that later reacted further with the chromite.

A Novel Reductive Alkali Roasting Of Chromite Ores For

A Novel Reductive Alkali Roasting Of Chromite Ores For

Sodium sulfate alone was found to be an unsatisfactory source of alkali for reaction with chromite. However when limestone also was added in quantities sufficient to allow the reaction CaCO3 Na2SO4 H20 Ca SO4 2NaOH CO2 to take place the results obtained were comparable to those found when sodium car-bonate was used.

Thermodynamics Of Chromite Ore Oxidative Roasting Process

Thermodynamics Of Chromite Ore Oxidative Roasting Process

For chromite particles in the size range -124 105 m the use of stoichiometric excess of sodium carbonate did not appear to increase the yield or the reaction rate significantly. However with smaller sized particles 8211 53 m increased yields of water-soluble chromate were obtained when roasted with more than the theoretical quantity of sodium carbonate.

Formation Of Chromiumcontaining Molten Salt Phase

Formation Of Chromiumcontaining Molten Salt Phase

Keywords chromite ore oxidative roasting molten salt phase NaOH KOH chromium recovery 1. Introduction Le Chatelier in the 19th century first applied alkali roasting in oxidising conditions for the extraction of sodium chromate from chromite ores 1 2. This discovery formed the basis for

Kinetics Of Chromite Ore In Oxidation Roasting Process

Kinetics Of Chromite Ore In Oxidation Roasting Process

The traditional lime-free roasting process used for manufacturing chromate from chromite ore has low oxidation rate which impact the chromate production efficiency and chromium recovery rate .

Comparative Study Of Alkali Roasting And Leaching Of

Comparative Study Of Alkali Roasting And Leaching Of

DING Yi. Present status and prospect of chromate production in China J. Chemical Industry and Engineering Progress 2004 234345348. in Chinese

Comparative Study Of Alkali Roasting And Leaching Of

Comparative Study Of Alkali Roasting And Leaching Of

ANTONY M P JHA A TATHAVADKAR V D. Alkali roasting of Indian chromite ores Thermodynamic and kinetic considerations J. Mineral Processing and Extractive Metallurgy 2006 1152 7180.

Conversion Of Chromium Ore Processing Residue To

Conversion Of Chromium Ore Processing Residue To

HAN Deng-lun ZHANG Zhong-yan LI Yuan-kui. Non-calcium roasting method of production chromium salts China Patent CN1579947 P. 2005-02-16. in Chinese

Roasting An Overview Sciencedirect Topics

Roasting An Overview Sciencedirect Topics

JAGUPILLA S C MOON D H WAZNE M. Effects of particle size and acid addition on the remediation of chromite ore processing residue using ferrous sulfate J. Journal of Hazardous Materials 2009 168 121128.

Alkali Roasting Of Chromite Ausimm

Alkali Roasting Of Chromite Ausimm

s J. HULTMAN ETAL PROCESS OF ROASTING CHROMITE ORE Aug. 15 1967 3336102

Us3336102a Process Of Roasting Chromite Ore To Produce

Us3336102a Process Of Roasting Chromite Ore To Produce

0 0 001mm 5 r0 mow J4 rrokvn United States Patent Ofiiice 3336102 PROCESS OF ROASTING CHROMITE ORE TO PRODUCE SODIUM CHROMATE Stanley J. Hultman George L. Rich Donald B. Bailey

Thermodynamics Of Chromite Ore Oxidative Roasting Process

Thermodynamics Of Chromite Ore Oxidative Roasting Process

Abstract. To explicate the thermodynamics of the chromite ore lime-free roasting process the thermodynamics of reactions involved in this process was calculated and the phrases of sinter with different roasting times were studied.

Biological Enrichment Of Chromite Ore On Alkaline Roasting

Biological Enrichment Of Chromite Ore On Alkaline Roasting

In theUnited States the roasting operations of this type have conventionally been conducted in long rotary kilns which are essentially heated cylinders in which the mixture to be roasted is fed in at one end and the roasted material exits from the other end while the cylinder rotates. This process while successful commercially is open to certain objections.

Formation Of Chromiumcontaining Molten Salt Phase

Formation Of Chromiumcontaining Molten Salt Phase

In the first place it is diflicult to seal from the surrounding atmosphere. Consequently dusts which are formed in the kiln as the roast tumbles therein frequently escape in gaseous suspension from the kiln. Since chromium in hexavalent form has a degree of toxicity the atmosphere adjacent an operating rotary kiln can produce a health hazard.

Us3816095a Method For Recovering Chromium Values From

Us3816095a Method For Recovering Chromium Values From

Because of the intrinsic objections to a rotary kiln and because horizontal hearths are more easy to seal it has been proposed to make use of such hearths in order to roast the chromium ore-alkali mixtures. Apparently this process has achieved some success in Europe although it has not heretofore been successfully applied in the United States.

The Chromothermic Reduction Of Chromite

The Chromothermic Reduction Of Chromite

In the investigation of the horizontal hearth process resulting in the present invention a number of ditficulties have been observed. In the first place serious difliculty has been encountered in obtaining complete or substantially complete solubility of the chromium. Furthermore the roasting operation particularly the oxidation of the chromium from trivalent to hexavalent state was found to take place at an unduly slow rate. This resulted in low outputs of the furnace. In addition an unduly high heat consumption has been observed as well as substantial dust losses out the stack.

Chromium A Thoroughly Modern Metal Dartmouth Toxic

Chromium A Thoroughly Modern Metal Dartmouth Toxic

In accordance with this invention a mixture of chromite ore a sodium carbonate and lime is deposited in the form of a layer upon a rotating horizontal hearth in a furnace. The hearth is heated by directing burning gas over the layer usually in a horizontal direction and transverse to the direction of rotation of the hearth.

Conversion Of Chromium Ore Processing Residue To

Conversion Of Chromium Ore Processing Residue To

In order to ensure oxidation of the chromium from trivalent to hexavalent state air is fed into the space above the layer of ore undergoing roasting. However to achieve the results discussed above the manner in which the air is introduced is of considerable importance.

Thermodynamics Of Chromite Ore Oxidative Roasting Process

Thermodynamics Of Chromite Ore Oxidative Roasting Process

Feb 04 2011nbsp018332To explicate the thermodynamics of the chromite ore lime-free roasting process the thermodynamics of reactions involved in this process was calculated and the phrases of sinter with different roasting times were studied. The thermodynamics calculation shows that all the standard Gibbs free energy changes of the reactions to form Na2CrO4 Na2O183Fe2O3 Na2O183Al2O3 and Na2O183SiO2 via chromite .

Physical Chemistry Of Roasting And Leaching Reactions For

Physical Chemistry Of Roasting And Leaching Reactions For

M.P. Antony et al.The soda-ash roasting of chromite ore processing residue for the reclamation of chromium Metallurgical and Materials transactions B 32 B 2001 987995. CrossRef Google Scholar

Extraction Method Of Chromium From Its Ore

Extraction Method Of Chromium From Its Ore

Abstract Oxidative alkali roasting of chromite is the state-of-the-art process for manufacturing chromium-containing chemicals which involves dealing with serious environmental problems arising from handling Cr 6-containing wastes generated in this processIn this article a new method for the extraction of Cr 2 O 3 from chromite ores is .

Crystals Free Fulltext Preparation Of Potassium

Crystals Free Fulltext Preparation Of Potassium

In the present investigation the oxidizing roasting process of chromite with sodium carbonate to prepare potassium dichromate crystals was studied in the microwave field with air by heating the chromite and sodium carbonate. The chromite and sodium carbonate heated separately at 1000 176C in the microwave oven frequency 2.45 GHz power 1.5 kW in order to study the microwave absorption .

40 Cfr 167 6311412 What Definitions Apply To This Subpart

40 Cfr 167 6311412 What Definitions Apply To This Subpart

Roasting means a heating oxidizing process where ground chromite ore is mixed with alkaline material such as soda ash sodium bicarbonate and sodium hydroxide and fed to a rotary kiln where it is heated to about 2000 F converting the majority of the chromium in the ore from trivalent to hexavalent chromium. Sodium chromate means Na 2 CrO 4.

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