老挝巴勉石英脉型金矿石工艺矿物学研究

Process Mineralogy of Quartz Vein Gold Ore in Bamian,Laos

为了查清老挝巴勉石英脉型金矿石中Au元素赋存状态,采用化学多元素分析、显微镜鉴定、MLA矿物参数自动分析系统、扫描电镜和能谱分析等方法对金矿石的化学成分、矿石结构构造、矿物组成和自然金赋存状态等工艺矿物学参数进行了详细研究。结果表明:老挝巴勉金矿石类型属于少硫化物石英脉型金矿石,非金属矿物主要为石英和斜长石,其次为绢云母、方解石和绿泥石;金属矿物主要为毒砂、黄铁矿和褐铁矿,含金矿物主要为自然金,自然金平均成色达905.09‰;自然金赋存状态以裂隙金为主,其次为粒间金(裂隙金和粒间金的总和为93.00%),包裹金很少;自然金粒度以中—细粒明金为主;载金矿物主要为毒砂,其次为黄铁矿、闪锌矿和石英。金的赋存状态表明:自然金易解离,采用重选—浮选联合流程,在-0.074 mm含量占75%的磨矿细度下,可以获得金总回收率95.54%的选别指标。

The technological type of ore in Bamian,Laos is low sulfide and quartz vein gold ore among which the main recycled element is gold with the grade of 42×10^(-6).The process mineralogy of gold ore was researched by microscope identification,SEM observation,MLA analysis,EDS analysis and multi-element chemical analysis.In order to find out the occurrence state of gold and provide process mineralogy data support and theoretical basis for the subsequent process design of beneficiation.The results show that:(1)The precious metal mineral is natural gold,which is the main recovered element.The main non-metallic minerals are quartz and plagioclase,the main metallic minerals are pyrite and arsenopyrite,followed by sphalerite.(2)A total of 165 natural gold particles were found in the ore,and the gold minerals are mainly natural gold which average purity is 905.09‰.The shape of natural gold is complex,mainly for the horn-granular and long-granular.The grain size of natural gold is coarser,which included 79.84%of visible gold,and 20.16%of micro gold.(3)The occurrence types of gold included 52.67%of fissure gold,40.33%of intergranular gold and 7.00%inclusion gold.(4)The main gold bearing minerals are arsenopyrite,pyrite,sphalerite,quartz and tourmaline,which closely symbiosis.The occurrence state of gold shows that the main natural gold is fissure gold and intergranular gold,the total of which is 93.00%.Moreover,the granularity of fissure gold and intergranular gold is relatively coarse.Usually the gold in this ore is easy to liberate.The arsenic in gold concentrage will exceed the standard because of the arsenopyrite is the main gold bearing mineral and arsenic bearing mineral.Through the unite gravity-flotation separation process,the gold recovery can reach to 95.5%under the grinding fineness of-0.074 mm 75%.The results of this study have found out the occurrence state of gold,filled in the blank of process mineralogy of quartz vein type gold ore and provided the basis for the process design of beneficiation.