低温条件下有机酸对铁、铜的淋滤实验研究

EXPERIMENTAL STUDY ON LEACHING OF IRON AND COPPER BY ORGANIC ACIDS AT LOW TEMPERATURES

水／岩作用实验研究表明，在低温条件下柠檬酸、草酸和酒石酸对岩石中的铁、铜都有很高的淋滤率。这表明，在表生地质作用过程中有机酸对成矿元素有很强的活化能力。实验研究同时发现，有机酸对成矿元素的活化能力受其分解温度的限制，由于大部分有机酸的分解温度都在２５０℃以下，因而有机酸对成矿元素的活化仅限于低温条件。本次研究还显示，判断一种岩石能否成为矿源层，不能简单的以其中成矿元素的含量高低作为标准，其中更关键的因素是元素在岩石中的存在形式，如果成矿元素在岩石中难以活化的形式存在。

Experimentation was made on leaching of iron and copper from wall rock of Masongling copper deposit in Pengxian County,Sichuan Province with citric acid,oxalic acid and tartaric acid (0 1 mol)at low temperatures(50 ℃,75 ℃)in a short reaction period(9 days).The experimental studies indicate that the leaching rate of iron and copper by the three organic acids at low temperatures is high,and increases with rising reaction temperature.The results show that organic acids can stimulate strong mobilization capability of ore forming elements during supergene geological activity.Different organic acids exert different mobilization abilities because of their different chemical properties.The mobilization ability of tartaric acid is lower than that of citric acid and oxalic acid.The experimental results also demonstrate that the mobilization ability is conditioned by decomposition temperatures of organic acids.The decomposition temperatures of most organic acids are below 250 ℃,that is to say,the mobilization of ore forming elements takes place only at low temperature.The study shows clearly that the problem whether one kind of rock can provide ore forming elements or not cannot be determined only by the concentration of the ore forming elements in the rock.The much more important factor is the modes of occurrence of the elements in the rock.If the elements exist in an inactive form in the rock,they cannot be mobilized even though the concentration of these elements is high.Moreover,the leaching rate is controlled by chemical properties of ore forming elements.The active elements are mobilized more easily than inactive elements at the same experimental conditions.