Polarisation curve CLPC

Two of these methods, the Contact Polarisation Curve (CPC) and the Contactless Polarisation Curve (CLPC) are used to investigate ore bodies with electronic... 

Ryss, Yu.S., 1979. The contactless polarisation curve (CLPC) technique for geophysical anomaly estimation and prospecting for economic ores in the prospective zones. In Principles and Techniques of Exploration, Rotaprint VITR, NI27 5-17 (in Russian). 

Processing of CPC and CLPC data includes determination of the electrochemical reaction potentials that take place on the surface of an ore body. For CPC data this is done directly using the polarisation curves from the ore body for CLPC it is necessary to use additional processing and calculations. Matching these potentials with the corresponding tabulated potentials affords estimation of the mineral composition of the... 

Both current electrodes, A and B, are placed in the host rocks on ground surface (Ryss, 1973, 1983). Current, as a linear function of time, is introduced into the ground by means of these electrodes (Fig. 2-45). If there is an electron-conducting ore body at depth this current flows into the ore body at one end (the zone of cathodic polarisation) and flows out of the ore body at the other end (the zone of anodic polarisation). This results in a potential difference with different signs and values in different parts of the ore body. This double electrical layer creates a secondary electrical field in the host rocks that can be measured by means of the measuring electrodes, M and N. For this measurement electrode M is moved along a profile to successive positions M), M2,. .M whilst electrode N is placed at infinity (Fig. 2-45). For each position of electrode M the CLPC polarisation curve is recorded. This curve is dependent on current I in the... 

Fig. 2-46. Shapes of polarisation curves of the same surface of an electronic conductor for (1) CPC method and (2) CLPC method (reproduced with permission from Putikov, 1993).

Fig. 2-47. Shapes of different types of CLPC polarisation curves in a profile over an ore body under polarisation CA- cathodic-anodic AC- anodic-cathodic C- cathodic zone of polarisation of ore body A- anodic zone of polarisation of ore body ci), (02, (O4, (O5- angles of visual range of polarisation zones for points M, M2, M4, M5 respectively (reproduced with permission from Putikov, 1993).

In summary, the main features of CLPC polarisation curves (and their dissimilarities with CPC polarisation curves) are as follows. 

In the CLPC method two types of polarisation curves CA and AC, are recorded, corresponding to the opposite directions of current. In order to increase productivity it is desirable to record simultaneously all polarisation curves at positions Mj, or at... 

Fig. 2-48. Example of CLPC data interpretation (A) anodic-cathodic (AC) and cathodic-anodic (CA) polarisation curves for stake 13 and stake 15 (B) curves of lAtp l along profile for the second cathodic process at the southern part (continuous line) and at the northern part (dotted line) of ore body (C) interpretation results of the experimental curves I Atpa I by means of the theoretical curves forh/ro=l (reproduced with permission from Ryss, 1983).

For interpretation of CLPC data two relationships are used (1) the dependence of the apparent differences of potentials of two sequential reactions Atp, at a distance y along a profile, Atpa = f(y) and (2) polarisation curves. Using these it is possible to determine the size of an ore body projection to the surface measuring profile, the mineral composition of an ore body and reserves of minerals. Ryss (1983) describes an example of CLPC data interpretation on a section at Rudny Altay (Fig. 2-48). The end faces of the horizontal ore bodies correspond to extremes of Acpa(y) (Fig. 2-48B). The group of ore bodies is considered as a horizontal cylinder with radius ro, depth of axis h. Also we... 

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