Factors affecting the rates of oxidation and reduction of liquid copper during fire refining
By: by Tanai Lérac Marín Alvarado.
Published: 2006
Language: eng
Number of pages: 240
ISBN-13: 9780494160244
Description: The results from top blowing of CO/N2, H 2/N2 and CO/H2/N2 mixtures show that hydrogen is a more efficient reducing reagent than carbon monoxide. The rate of reduction is proportional to the flow rate of either H2 or CO 2. From these results the rate of reduction with top blowing reducing O2/CH4 flames can be estimated and are in good agreement with experimental results. For the first time, it was observed during the reduction of liquid copper with top blowing CO/H2/N2 mixtures a sudden acceleration in the rate of reduction due to the dissolution of hydrogen into the melt and its reaction with dissolved oxygen to form H 2O gas bubbles inside the liquid bath.The rates of liquid copper oxidation and reduction plays an important role in the separation of impurities from copper during fire refining. However, the importance of the different factors affecting the rate of oxygen uptake by liquid copper and the rate of reduction with combustion gases is not clear. In this investigation, both oxidation and reduction with top blowing combustion gases were studied experimentally.Top blowing oxidation of molten copper shows that the rate of oxidation is almost independent of the average oxygen concentration in the copper and proportional to the oxygen flow rate of the gas mixtures used. A pressure monitoring technique was used to determine the effect of the presence of a carrier gas such as N2, He and CO2, the effect of the lance distance from the liquid surface and on the partial pressure of oxygen in the gas phase. At large separations between the tip of the lance and the liquid surface, the rate depends on the presence of a carrier gas and on the partial pressure of oxygen in the gas phase. When the lance is close to the surface, the rate increases dramatically and becomes independent of the other factors. This is explained by surface tension driven flows due to a gradient of oxygen concentration along the surface. A transient finite elements analysis, considering fluid flow coupled with mass transfer, was developed to help understand the mechanism of oxygen mass transfer into the molten copper.
Notes: Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 4079.

Thesis (Ph.D.)--University of Toronto, 2006.

Includes bibliographic references.

Electronic version licensed for access by U. of T. users.