NIOSHTIC-2 Publications Search

Kinetics and mechanism of the conversion of covellite (CuS) to digenite (Cu1.8S).

Authors
Shah-ID; Khalafalla-SE
Source
Metall Trans 1971 Sep; 2(9):2637-2643
NIOSHTIC No.
10010245
Abstract
Rates of conversion of covellite (cus) to digenite (cu1.8S) in n2 and various partial pressures of o2 have been studied in the temperature range 260 deg to 400 deg c. The reaction is first order with respect to o2 concentration in n2-o2 mixtures at 1 atm. The experimental activation energy for the conversion of cus to cu1.8S is 23 +/- 3 kcal. In a nitrogen atmosphere, the conversion proceeds at a slower rate but with the same activation energy and leads to the formation of elemental sulfur instead of so2. An externally added small amount of iron powder (0.6 percent) increased the rate of conversion but had no effect on the apparent activation energy. The rate-controlling reaction in the conversion mechanism is postulated to be cu1.8S -> 1.8 Cu+ + 1.8 E- + s at the cu1.8S/gas interface. Reduction of cus by copper(I) ions and electrons occurs by a rapid reaction, 0.8 Cu+ + 0.8 E- + cus -> cu1.8S at the cus/cu1.8S interface, which steadily contracts with time.
Keywords
Chemical-reactions; Chemical-properties; Chemical-kinetics; Gas-mixtures; Gases
CODEN
MTTBCR
Publication Date
19710901
Document Type
OP; Journal Article
Fiscal Year
1971
Identifying No.
OP 184-71
ISSN
0360-2141
NIOSH Division
TCRC
Source Name
Metallurgical Transactions. B. Process Metallurgy
State
MN
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division