1、中文 1700 字，英文 1200 单词 外文文献翻译 题 目： 学院名称： 指导教师： 职 称： 班 级： 学 号： 学生姓名： 二 一 年 月 英文文献翻译 原稿： New Chloride Leaching Process for Gold Extraction from Refractory Ores WS Rapson Abstract： The extraction process of gold and silver from the gold clay ore containing arsenic and manganese was investigated With the
2、conventional technique the leaching rates of gold and silver are 78 23 and 49 02， respectively To eliminate the negative efects of arsenic and manganese on cyanidation and increase the gold and silver leaching rates， a novel catalyst was added The content of the catalyst used in the process was 8 gp
3、er 500 g org sample， the sample size was 60 prn andthe pH value was kept between l0 and 11 Leaching with the catalyst for 3-5 h under certain conditions， the gold leaching rate increased to over 90 and the silver leaching rate increased to 80一 90 Th e catalyst can efectively liberate gold and silver
4、 from the enclosure of arsemc and manganese and the industrial experiment has great significance to the development and utilization ofthe gold clay ore containing arsenic and manganese. 0.Introduction From certain gold ores, known as refractory gold ores, the gold cannot be fully recovered by direct
5、 cyanide leaching. A major cause of this is the occurrence of much of the gold in such ores in highly disseminated form in sulfide, arsenide and sometimes antimonide minerals. Three methods have been developed for treatment of such refractory ores, each of which involves breaking down the sulfide an
6、d arsenide minerals by oxidation before cyanide extraction. In one method, the sulfide and related minerals containing the gold are recovered by flotation, and roasted. The residues (S- and As-free) are then leached with cyanide. In a second, recently developed process, the flotation concentrates ar
7、e aerated in slurry form in a medium containing Sand As-oxidizing microorganisms before being leached with cyanide. In the third method, breakdown of the S- and As-minerals is achieved by oxidative treatment of the concentrate in an au toclave, followed by cyanide leaching. Method 1 is gradually bei
8、ng abandoned because of environmental pollution problems, and new plants in the USA, South Africa, Australia and elsewhere tend to employ Method 2 or Method 3, which produce less severe problems of this type. There are two factors affecting the extraction rate: one is the elements existing in the go
9、ld ore, and the other is the method used in the extraction process. Much research has been devoted to conventional gold ores , while few works has been published on gold ores containing manganese and arsenic. The cyanidation process has been the most important process in the extraction of gold and s
10、ilver for the past 100 years and the methods used to enhance the extraction rates in the cyanidation process have drawn much attention in recent years. Several researchers have studied the additive to enhance the leaching rates . Over the past 10 years, however, there have been a number of publicati
11、ons which indicate that the direct oxidative chloride leaching of gold from refractory gold ores may prove to be an improvement on the methods now in use. These new developments were reviewed by F K Lerowski of the University of Witwatersrand in Johannesburg, at the International Conference on the S
12、cience and Technology of Gold at Hanau in Germany in June 1996 (1). They include: 1 The use ofless volatile chloride ion carriers In the past, HCl has been used as the main chloride ion carrier in leaching solutions and HN03 (or C12) as the oxidant. This has limited leaching temperatures because hig
13、h partial pressures of HCl lead to loss of Cl from the leaching solution. Partial substitution of HCI by AlCI3 or ZnCl2 has been found to decrease dramatically these partial pressures of HCl, apparently as a result of the formation of AI and Zn chlorocomplexes. This has made the attainment of higher
14、 leaching temperatures and higher efficiencies possible. Decomposition of the refractory sulfides and arsenides occurs in the chloride leach solutions and their gold content made susceptible to cyanide leaching. The objective of this study was to analyze the interference characteristics of manganese
15、 and arsenic in the cyanidation process. The effect of a catalyst that could significantly enhance the leaching rate was also discussed and illustrated through experiments. 2 The regeneration, in process, of nitric acid used as oxidant In the chloride leaching reaction, the nitric acid is reduced to
16、 NO, the conversion of which back to HN03 is costly by conventional methods. A leaching in froth (LlF) process has been devised, however, which has been successfully applied on a laboratory scale for mineral graphite purification (2), zinc concentrate processing (3) and more recently for gold extraction from
