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Electrochemical effects on rock drilling.

Authors
Engelmann-WH; Watson-PJ; Tuzinski-PA; Pahlman-JE; Khalafalla-SE
Source
J Electrochem Soc 1988 Apr; 135(4):1043-1044
NIOSHTIC No.
10006600
Abstract
A strong correlation was found between drilling performance and the zeta potential at the rock-solution interface. Maximized drilling performance occurred where the ionic concentration produced a zero point of charge (zpc). At the rock zpc, the zeta potential is also zero. A model based on correlations between the electrical double layer profiled in the rock interfacial layer and lippmann's electrocapillarity curve is proposed to account for the observed phenomena. At the zpc concentration, the rock interfacial tension is maximized; drilling enhancement is also maximized, possibly because the rock is weaker in tension than in compression. Surface tension reducers are efficient in chemical crack propagation. Taking drilling as an activated cracking with catastrophic growth of microcracks into more destructive ones, it is possible that the interfacial tension, or surface energy, must first reach a critical tension before fragmentation occurs, with an overall lowering of the interfacial tension. This distinction between the kinetic process of drilling and the thermodynamic transition of crack formation explains why an increase in interfacial tension can facilitate drilling by lowering the energy barrier for rock fragmentation.
Keywords
Mining-industry; Mineral-processing; Metals; Author Keywords: rocks; electrochemistry; surface tension; electrokinetic effects
CODEN
JESOAN
Publication Date
19880401
Document Type
OP; Journal Article
Fiscal Year
1988
NTIS Accession No.
NTIS Price
Identifying No.
OP 8-89
Issue of Publication
4
ISSN
0013-4651
NIOSH Division
TCRC
Source Name
Journal of the Electrochemical Society
State
MN
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