# The Improvement and Application of the Geoelectrochemical Exploration Method
## 1 Introduction  
The geoelectrochemical exploration method (GEM), derived from CHIM (Chastichnoe Izvlechennye Metallov), was invented by Leningrad researchers in the late 1960s to early 1970s, and the method refers to partial extraction of metals. The systematic theory and field techniques, together with some practical results, were first published by [PERSON] and [PERSON] (1973) [1]. The laboratory results upon which the method is based, some additional field conditions, equipment parameters, and speed of coverage of the method were described in several other papers [1; 2; 3]. In the 1970s and 1980s, the CHIM method was extensively applied in Russia in exploration for base and precious metals, W, U, Be, and oil and gas [4]. In the early 1980s, experimental research was carried out in China [5; 6], and in the late 1980s, geoelectrochemical experimentation was started in India [7]. In the 1990s, this method was applied on a trial basis in the USA [8] and Canada [9], and then widely applied to search for concealed ore deposits [10; 11]. Since the 2000s, a large amount of research on the halo-formingmechanism of this method has been performed, and great progress has been made for its technique improvement [12; 13; 14; 15]. Excellent results of searching hidden ore deposits of Cu, Pb, Zn, Au, Ag, Sn, As and Sb have been obtained with this method [16]. Meanwhile, application studies have been carried out for different stages of mineral exploration, with great success [17; 18]. The CHIM method has been improved since it was put forward. MDI (Method of Diffusion Extraction) was first proposed for exploration of buried ore bodies by [PERSON] et al. (1981) [19], \"Dipole\" CHIM was proposed by [PERSON] (1993) [20], and NEOCHIM was set up by [PERSON] and [PERSON] (1993) [21]. More recently, the adsorption-electric extraction method was developed by [PERSON] (1992) [22], [PERSON] et al. (1997) [14], [PERSON] (1994) [23] and [PERSON] and [PERSON] (2000) [15]. However, there are still many disadvantages as follows:  
1. Formerly, researchers [1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11] intended to extract metal ions, under the influence of electric current, from a buried deposit through hundreds of meters of overburden into the element-collectors (ECs) on the surface. To achieve this, a large power generator is required, and each measurement point is connected with the generator by long wires. Procedures are complex, and the operation is inconvenient in field, e.g., the power is easily broken off by accidental factors, such as cars passing by, animal actions, and people walking, etc. 2. Element-collectors (ECs) filled with solution may leak, to a greater or lesser degree, so that the remaining amount of the solution is very different when the work is finished, which may have an influence on identifying anomalies. 3. Element-collectors (ECs) of the adsorption-electric extraction method have some advantages over the liquid-type ECs. Previous work, however, only employed a single cathode to extract ions that are in positively charged forms of elements. [PERSON] (1993) [20] proposed the \"Dipole\" CHIM method, which enables a simultaneous extraction of anionic and cationic species of elements, and the ECs have been improved greatly as well. However, it is difficult to use in field owing to its weight, complicated operation procedures, high cost and relatively low production rate. 4. The improvement of method has received only minimal attention in the English-language literature. [PERSON] et al. (2003) [12] and [PERSON] et al. (2006) [13] gave a brief overview of the development and application of the improved method in Chinese, with an English abstract. On the improvement of the CHIM method, the authors have carried out some exploration in China and made some progress [12; 13], and other researchers [24] also conducted related research. In order to carry out the research and further improve the technology of this method on a global scale, the authors systematically summarized the previous research results and wrote this paper.