摘要
将铅精矿或铜精矿样品30.00g平铺于预先铺有20g二氧化硅的方舟中,于试金炉中在750℃焙烧脱硫60min。将脱硫后的样品混合物转移至黏土坩埚中,加入50g碳酸钠,200g氧化铅,20g四硼酸钠作为助熔剂,4.0g淀粉作为还原剂,搅匀后在表面覆盖约5mm厚的氯化钠,在试金炉中于1 100℃进行熔融(一次试金),获得30~40g的铅扣。将铅扣在850℃进行灰吹,得到金银合粒。将一次试金的熔渣和灰皿粉碎后置于一次试金用的坩埚中,加入40g碳酸钠,20g四硼酸钠,25g二氧化硅及4.0g淀粉,搅匀并在表面覆盖约5mm厚的氯化钠后,再进行火试金和灰吹处理,得到第二颗金银合粒。两次所得金银合粒合并后,用热硝酸(1+7)溶液进行分金。用重量法或原子吸收光谱法测得金量,用差量法得到银量(用电感耦合等离子体原子发射光谱法测定铜、铅、铋、砷和锑等杂质的含量)。回收试验得到金的回收率为99.2%~100%,银的回收率为100%,测定值的相对标准偏差(n=7)为0.37%~2.8%(金)和0.28%~2.4%(银)。
Sample of lead ore concentrate or copper ore concentrate(30.00 g)was smooth out on a layer of silicon dioxide(20 g)which was priliminarily placed on the bottom of a combustion boat and roasted for 60 min at750℃ in an assay furnace for desulfurization.The desulfurized sample mixture was then transferred to a clay crucible,and a flux mixture containing 50 g Na2 CO3,200 g PbO and 20 g Na2 B4 O7 together with 4.0 g of starch as reductant was added.After thorough mixing,and covering a layer of NaCl with its thickness ca.5 mm,the mixture was fused at 1 100℃in an assay furnace for the 1 st fire assay,and a lead button of 30 to 40 g was obtained.The lead button was cupelled at 850℃and a metal bead of gold and silver was obtained.The molten slag and cupel left from the 1 st fire assay were crushed and placed into the crucible used in the 1 st fire assay,and the 2 nd fire assay and cupellation were carried out in the same way as the 1 st assay and cupellation,except using less amounts of flux mixture(40 g Na2 CO3,20 g Na2 B4 O7 and 25 g SiO2),and a second metal bead of gold and silver was obtained.The two metal beads of gold and silver were put together and treated with hot HNO3(1+7)solution to separate gold from silver and other impurities.The gold was determined by gravimetry or by AAS,and the silver was determined by difference method(the impurities,i.e.Cu,Pb,Bi,As,Sb were determined by ICP-AES).Values of recovery found by test for recovery were in the range of 99.2% to 100% for gold and were 100% for silver,and values of RSDs(n=7)of determination values were ranged from 0.37%to 2.8%for gold and from 0.28%to 2.4%for silver.
作者
张全胜
孔令政
张雷战
杨昆昆
ZHANG Quansheng;KONG Lingzheng;ZHANG Leizhan;YANG Kunkun(Henan Yuguang Gold and Lead Co.,Ltd.,Jiyuan 459000,China)
出处
《理化检验（化学分册）》
CAS
CSCD
北大核心
2019年第8期932-936,共5页
Physical Testing and Chemical Analysis(Part B:Chemical Analysis)
关键词
火试金法
金
银
铅精矿
铜精矿
焙烧脱硫
fire assay
gold
silver
lead ore concentrate
copper ore concentrate
desulfurization by roasting
