【作者】 罗先熔；

【导师】 周涛发；

【作者基本信息】 合肥工业大学 ， 矿物学、岩石学、矿床学， 2005， 博士

【摘要】 随着地质找矿工作的不断深入,地表出露的与近地表的矿床大多已被发现,寻找深部隐伏矿成为当前各国地学家面临的重要课题,由此,勘查地球化学家一直在努力研究能探测更大深度的勘查地球化学方法。地电化学方法自20世纪70年代由俄罗斯学者提出后,倍受各国地学专家学者的关注,经实践检验,该方法勘探深度较大,寻找隐伏矿床效果较好,仍然是21世纪地学家们研究的主要课题。但基于地电化学方法在成晕机制方面存在的分歧、方法技术上存在的缺陷和方法应用上存在的局限,开展本论文的研究,进一步完善地电化学方法体系,并进行规范化和标准化,以期作为一套成熟的方法技术推广应用。论文主要开展了如下几方面的研究: 1、金属矿床电化学场基础理论研究 通过对成分均匀的单一矿物组成的矿体、多金属矿体、浸染状矿体形成的电化学电场的分析,从金属硫化矿物的电极电位出发,从本质上论述了金属矿床电化学场的形成机理:矿体不同部位的物质存在差异,或者矿体周围水溶液介质性质存在差异,都能产生自然电场。矿体的不均匀或围岩溶液不均匀都是一个电极电位问题。潜水面切割矿体时有利于产生自然电场,但矿体在潜水面之上或潜水面之下同样能产生自电异常,关键因素是矿体不同部位的电极电位差异。所以,矿物间不同的电极电位是产生电化学电场的根本原因,电化学电场是金属矿床产生自然电场的主要形式。 2、地电化学成晕机制研究 通过室内进行的金属矿体电化学溶解实验、人造矿体的电化学分散模式模拟实验,进行金属矿体的电化学溶解和离子以氧化还原梯度迁移机制的研究。 通过在广西大瑶山西侧北段盘龙铅锌矿进行的高电压（220V）和低电压（9V）地电提取实验研究、加入不同电解质溶液（水和13.6 HNO₃%的稀硝酸）的地电提取实验研究,在新疆210金矿、山东招远尹格庄金矿进行的通电条件下的地电提取实验研究和不通电情况下的泡塑电极吸附实验研究,对前人提出的地电提取成晕机制进行了辨证的否定,即:肯定了外加电场在地电提取过程中所起的重要作用,否定了在通电时将深部矿体或来自深部的离子直接提取到提取电极上的观点;肯定了地电提取的离子晕来自于近地表的浅部离子晕,但这种离子晕是动态的,否定了地电提取的离子晕只是来源于电极周围的土壤中的观点以及室内电吸附法可取代现场地电提取法的观点。 提出了“外电场作用下,提取电极周围的离子运移牵动着远处及深部离子迁移的递推理论”,即:金属矿床由于受到电化学作用,便产生电化学溶解,在矿体周围形成离子晕,在电化学电场、地气搬运、地下水运动等各种自然营力作用下迁移到近地表,地电化学成晕的物质来源就是这种近地表的离子晕,该离子晕来自于深部矿体,具有动态性。当有外加电场更多还原

【Abstract】 With the development of mineral exploration, most of the surface outcropping and near-surface ore deposits have been discovered, hence it becomes important for global geologists to search for deep concealed ore deposits. Therefore, geochemists have been working on various geochemical exploration methods to detect deep ore deposits all the time. The electrogeochemical method has been paid close attention by global geological geologists since it was first proposed by a USSR geologist in the 1970s. During the practice, the method is able to detect deeper ore deposits than conventional geochemical exploration methods, and can produce obvious effects. Thus it is still being studied as a main topic by geologists in 21st century. Because of different views in the halo-forming mechanism of the electrogeochemical method and disadvantages of the technique and its limitations in applications, some studies are carried out to improve the methodology system. In this way a mature set of methods and techniques is to be anticipated to be widely applied in our country. The studied contents of the thesis are as follows:1, Basic theory study of the electrochemical field on the metallic ore deposits.Through the analysis of the forming mechanism of electrochemical field of the ore bodies composed of single mineral and polymetallic ore bodies and disseminated ore bodies, the forming mechanism of the electrochemical field of the metallic ore deposits is expounded from the electrode potential of the metallic sulphide. That is: when the substance of different parts of ore body is different or the properties of the water solution media around the ore body are different, it induces different electrode potential, and natural electric field can be generated. Natural electric field is easy to be produced when ore body is crosscut by the water table; however , self-potential anomaly can also be produced when the ore body is over or below the groundwater table. The key factor is the difference of electrode potential among the different parts of the ore body. In general, the different electrode potential among minerals is critical to generate electrochemical field, and such an electrochemical field is the main form of natural electrical field for the metallic ore deposits to produce.2. The study on the mechanism of electrogeochemical halo-formationAfter doing the experiment in electrochemical dissolution in the lab and simulated experiment in the model of element dispersion around an artificial sulphide ore body, the study of the mechanism of electrochemical dissolving on metallic ore body and the migration of redox gradients of ions was carried outExperiments have been done on the electrogeochemical extraction electrified by high voltage (220V) and low voltage (9V) at the Panlong lead-zinc deposit in Dayao mountains, Guangxi, added by different electrolyte solution (water and solution of 13.6% HNO3), and onthe electrogeochemical extraction under artificial electric field as well as adsorption of foamy plastics electrode without artificial electric field at the 210 gold deposit in Xinjiang and at Yingezhuang gold deposit in Zhaoyuan, Shandong. We dialectically negates the existing halo-forming mechanism of electrogeochemical method. It is confirmed that the artificial electric field plays an important role in electrogeochemical extraction, and that the ions from the ore body are not directly extracted to element-colIectors(ECs) under artificial electric field. Meanwhile, it is confirmed that the ionic haloes in the electrogeochemical extraction come from near the surface, which are dynamic, and that the ionic haloes in the electrogeochemical extraction don’t only come from the soil around the electrodes, and that indoor electric adsorption can not replace the on-the-spot electrogeochemical extraction.A new theory is advanced to propose that the ionic movement around ECs induces the migration of ions at distance and depth under the influence of the artificial electric field. Namely, the metallic minerals are dissolved under the electrochemical effects to create ionic haloes around the ore bodies, which migrate up to the near surface affected by various natural agents such as electrochemical field, earthgas, groundwater movement and so on. The source of the electrogeochemical haloes are just the near surface ions that come from the deep ore body and are the characteristics of dynamics. The artificial electric field activates and changes the bound forms of occurrence of elements in the soil, on one hand, to bring about decomposition of a great number of complex anion and other stable or sub-stable form of elements, and on the other hand, makes anions and cations move to the extraction electrode, and it accelerates the ionic movement The redox reaction around the electrodes gradually moves the ions and transfers charges which reside farther, more interior and deeper from the center of electrode, which breaks the balance of the primary redox potential field between the deep country rock and the overlying overburden. To maintain the new balance, the ions moving away from an unit volume need to be supplemented by the ions from the adjacent unit volumes. Thus, the ions of dynamic balance migrate up one by one like a relay race. If there are ore bodies under the ground, the metallic ions produced by the electrochemical dissolution of the ore bodies will migrate continuously up to form an ionic haloes of dynamic balance. Although the movement velocity of single ion is low, and the migration distance of single ion is sbort numerous ions transmit one by one to achieve migration from long distance.3-. Study on the method and technique of electrogeochemical prospecting 1) Kind study of geoelectro-extractionThe kinds of geoelectro-extraction include:shallow electro-extraction deep electro-extraction charge electro-extraction logging electro-extraction water electro-extraction etc,on the basis of the difference of the geoelectro-extraction excitement way it may be divided into two kinds:high-power excitement and low-power excitement,and they are widely used in China.So the paper emphasizes the contrast study between high-power excitement and low-power excitement,the result indicates that there are both clear electrogeochemical anomaly no matter which kind of way,now we can’t simply affirm any kind,however,deny another because any kind has its own excellence and flaw,we must choose appropriate way on the basis of different condition and different request,and use selectively on the basis of different phase of ore-search.2) Study of distilling electrodeThis is one of important problems of geoelectro-extraction technique.the selection of the distilling electrode directly affects the distilling result,The paper analyses and contrasts main kinds of electrode throughout the world,The new type solid electrode which has strong absorption ability to the ion of heavy metal and precious metal has been made.Many tests have been operated with the electrode in house and field,and contrast tests have been operated in Au-. Sn-. Cu-. Sb deposits etc between the electrode and other electrodes.The result shows the new electrode has better effect The excellences include-.high sensitivity-, detecting depth is large-, kinds the new electrode can detect are excessive, we can get different anomaly between surface mine and deep mine with the new electrode,anomaly basically is affected by structure,good applicability to all heavy and precious metals and settling basification matter.3) Criterion study of way and techniqueBecause effect factors of electrogeochemical measurement are very excessive and measurement data is affected by many condition (for example:specification of kryptoK plastic and filter paper- distilling liquid-, distilling time and unit of data etc) .So it is necessary that the technique is standardized.According to plentiful tests that I have done ,1 bring forward a set of applied standard inthe paper,we have acquired better effect with the standard in prospecting for ore deposits.4- Feasibility study of electrogeochemical methodFor study effect of electrogeochemical method in prospecting for hidden polymetallic deposits we have studied the feasibility in typical hidden polymetallic deposits-, all kinds of thick-bedded cover areas-, different cause of formation and different types.We have studied the feasibility in seven Au deposits-, two Cu deposits-, two Pb> Zndeposits-. two Wu-. Sn deposits and three other polymetallic deposits,and there are all clear electrogeochemical anomaly above the sections of above-mentioned mining areas.lt suggests that electrogeochemical method is effective in prospecting above-mentioned kinds of hidden polymetallic deposits and the method can be widely used in prospect ore deposits.5-. Application study on electrogeochemical method for different stages of mineral exploration1) Application at regional exploration for electrogeochemical methodThe improved CHIM is first proposed to be applied at the regional level to identify prospective target areas because it is portable, easy to operate, practical, low cost and efficient in the fieldwork. Tests were conducted to an area of 22.5km2 by 500mx500m investigation at Jinwozi to No. 210 gold ore belt in Xinjiang, six gold anomalies, four silver anomalies, three copper anomalies are discovered. At known gold mineralization, two CHEVI assemblage anomalies for Au, Ag, Cu were observed, which are of obvious concentration center, a certain concentration gradient, continuous anomaly points, and the composition of identified haloes correlates well with the position of the concealed mineralization. Around known gold mineralization, two CHEVI assemblage anomalies for Au, Ag, Cu were identified. These showed that CHIM method can be feasibly applied at the regional mineral exploration, which helps change the case that previous CHEVI method is only used for detailed exploration and at the assessment stage for verifying the geophysical and geochemical anomalies.2) Application to detailed exploration for electrogeochemical method? A research on an area of 0.96km2 for detailed exploration was carried out in order to search for deep ore deposits at the Xinzao lead-zinc mining area in Dayao mountains, GuangxL The distinct CHlM anomaly is given over the known lead-zinc ore body, and concentration center of anomalies for Cu, Pb, Zn correlate well with the position of the concealed ore body, and a predicted mineralization belt of an proximate 1.2 kilometer long was circled in the periphery of the mining area.? A research of a 1.02km2 area for detailed exploration was carried out in order to search for concealed gold deposit at the Luanjiahe fault in Zhaoyuan, Shandong. In the west part of the study area, four parallel linear anomaly belts were discovered, whose direction of stretch is in the similar direction of the extension of the fault in the area. Multi-elements anomalies of the anomaly belts are strong, and are characteristics of elements assemblage. In the east part of the study area, four anomalies of Au, two anomalies of Ag, four anomalies of As, two anomalies of Sb, three anomalies for soil ionic conductivity were discovered, which are characterized by linear. These provide important clues for further assessment of the ore potentiality of the fault.(D A research of a 0.2km2 area for detailed exploration was carried out in order to study the perspective of prospecting mineral deposits at the Taifu gold mining area in Heng County, Guangxi. Five electrogeochemical anomaly belts were circled, and gold ore bodies were discovered 100 m below the surface under JV-1 anomaly and IV-2 anomaly of IV anomaly belt through prospecting while mining, whose average grade is 5.4x10"*. Gold mineralization was discovered in drill hole of II -1 anomaly of II anomaly belt. Gold mineralization bodies were also discovered in prospecting trenches of V-2 anomaly, and whose average grade is 2.063X10-6.This research finds out that the electrogeochemical method is a better prospecting method to search for concealed ore deposit, which can be applied at all stages of mineral exploration through method and technique improvement, and it can also be applied in the most areas in China. Therefore, the working standards of the soil ionic conductivity method and the improved CHIM are made so as to be widely applied as a mature set of method and technique for mineral exploration.更多还原