金矿预氧化处理过程中砷的转化

Arsenic Conversion During Pre-Oxidation Treatment of Gold Ores

含砷难处理金矿组成复杂,需经过预氧化处理才能进行氰化提金。砷的转化方式和最终形态对含砷难处理金矿的预氧化处理效果有重要的影响。目前难处理金矿的预氧化方法主要有3种,分别是焙烧法、加压氧化法和生物氧化法。围绕砷的转化问题,综述了3种难处理金矿预氧化处理方法的优缺点,并结合我国黄金工业的发展现状和环境保护要求,展望了难处理金矿预氧化处理技术的未来发展方向。

The composition of arsenic-bearing refractory gold mine is complex,in which gold is usually encapsulated by arsenopyrite and arsenian pyrite.Arsenic is a poisonous element,which is harmful to human health and has adverse effects on the ecological environment.At the same time,the arsenic-bearing ores can lead to excessive consumption of cyanide and affect cyanide leaching of gold.Therefore,the arsenic-bearing refractory gold ores need to be pre-oxidized before cyanide leaching.The transforming pathway and final form of arsenic have an important effects on the pre-oxidation treatment of arsenic-containing refractory gold ore.At present,there are three pre-oxidation methods for refractory gold ores,namely roasting process,pressure oxidation and bio-oxidation method.Roasting is a proven technology,which can comprehensively recover copper and arsenic,but it is difficult to avoid the release of arsenic in this process.The pressure oxidation is an environment-friendly process that can achieve high gold recovery,but the expensive pressure reactor used in this process will lead to a high capital cost.Bio-oxidation method can obtain a recovery rate close to that of the pressure oxidation method,and the equipment investment cost is much lower than that of the pressure oxidation method.However,the bio-oxidation reaction is slow and a longer residence time is needed.The long residence time and the low efficiency of bio-oxidation treatment,especially the slow oxidation and decomposition rate of low-arsenic minerals,restricts its further development.It may face competition from pressure oxidation in the future.However,if it can be combined with roasting process,it is possible to improve the roasting process with its own environmental advantages in arsenic treatment to form a gold ore treatment technology with both advantages of clean production and efficient treatment.The advantages and existing problems of these preoxidation methods for refractory gold ores were reviewed in this paper with emphasis on the conversion of arsenic.Considered the development status of Chinese gold industry and the requirements of environmental protection,the basic development direction of pre-oxidation for refractory gold ores in the future was prospected.With the wide application of arsenic-containing refractory gold ores,the decomposition of arsenic-containing ores by pre-oxidation has become a common process for gold extraction.The pre-oxidation process should consider not only the gold extraction efficiency,but also the safe disposal of arsenic-containing waste.With the increasing of environmental concerns,the requirements of cleaner production even exceed the requirements of production efficiency.The common development of clean production and efficient production is the main trend of current development.