Research On The Structure Of Carbonaceous Matters And Preg-robbing In Carbonaceous Gold Ores

Carbonaceous gold ores which contain carbonaceous matters is a kind of refractory gold depoits.The researches show that carbonaceous matters in carbonaceous gold ores can rob gold in the process of cyanidation leaching,resulting in reduce the leaching rate of gold seriously and bring economic loss to the enterprise.Therefore,in this paper,the gold concentrate and pressurized oxidation slag of a certain carbonaceous gold ores from Guizhou Province were took as raw materials.The elemental carbon,humic acid and fulvic acid extracts were extracted and characterized,and then analysed and compared their"preg-robbing" ability.The aim was to provide theoretical basis and data guidance for the t structural ransformation of carbonaceous matters and the change of "preg-robbing" capacity before and after pressurized oxidation.The structural analysis of the elemental carbon extract showed that:the elemental carbon particles were mainly block-shaped,and the surface was a layered structure with many pores.the degree of crystal defects,graphitization,and specific surface area of the elemental carbon extract were between graphite and activated carbon;In the structure,it contained both crystalline carbon and amorphous carbon.the extract of elemental carbon contained aromatic structure and oxygen-containing functional groups such as alcohol,ether,ester,phenol and carbonyl group.The structural analysis of humic acid extracts showed that:humic acid molecules existed in a spherical structure and were prone to agglomeration.Humic acid in gold concentrate contained hydroxyl groups,aliphatic CHx,carboxyl groups,carbonyl groups,aromatic rings,amide groups,and aromatic sulfonic acids.Although the functional groups composition of humic acid in the pressurized slag was similar with humic acid in gold concentrates,its aromaticity was relatively low,and the degree of degradation of phenol/quinone core to simple aromatic carboxyl structure was relatively low in molecular structure,and the degree of aromatic ring condensation and average molecular weight were high.The structural analysis of fulvic acid extract showed that:fulvic acid in gold concentrate contained oxygen-containing functional groups such as hydroxyl,carboxyl,carbonyl,and ether,amide and aromatic rings.In spite of the functional group composition of fulvic acid in pressurized slag was similar to that of fulvic acid in gold concentrate,the fulvic acid in pressurized slag contains more oxygen-containing functional groups,and has a higher aromatic degree,a smaller number of chromophores,and the degree of the phenol/quinone core was degraded to a simple aromatic carboxyl structure was relatively lower than fulvic acid in gold concentrates.In addition,the degree of aromatic ring condensation and average molecular weight were also low.The "preg-robbing" experiments of elemental carbon extract and humic acid extract showed that:the adsorption rate of elemental carbon extract was 80.4%;its "preg-robbing"ability was higher than that of graphite,and was closed to that of activated carbon.The adsorption rates of humic acid in gold concentrate and humic acid in pressurized slag were 56.6%and 42.8%,respectively.After pressurized oxidation,elemental carbon was effectively decomposed,however,the organic carbon matters such as humic acid still existConsequently,humic acid has a certain adsorption capacity for gold,it will generate a"preg-robbing" effect in the cyanide leaching stage,which reduce the gold leaching rate,affecting the recovery of gold adversely.