关键词: 自然金, 尼尔森重选, 液态化水量, 重力倍数, 浮选

Abstract: A low-grade gold deposit in Henan province are characterized by uneven grain size， wide grain size distribution and serious gangue inclusion， which makes it difficult to recover the gold minerals. In order to improve the recovery rate of the gold， a series of beneficiation experiments were carried out on the basis of mineral processing. The results showed that:①the main useful mineral of the raw ore is native gold. The gold grade is 1.39 g/t in the raw ores. The grade of the siliver is 3.35 g/t， which could be recycled as the associated metal. The secondary metal minerals are mainly pyrite， with a small amount of chalcopyrite， magnetite， bismuth and galenite. The gangue minerals mainly are quartz， plagioclase， chlorite， mica， dolomite and calcite， followed by a small amount of amphibole. ②Gold particles mainly exist in the form of wrapped gold accounting for 58.83%， followed by cracked gold accounting for 23.53% and intergranular gold accounting for 17.65%， in which the gold in quartz accounting for 19.11% of the gold. ③Under the best test conditions， the combined process with gravity separation and flotation was adopted. After three times Nelson gravity separation and one cleaning with shaker， the heavy separation tailings were floated by one roughing， two cleaning and two scavenging. Finally， the gravity sand contains 986.60 g/t of gold， the gold recovery rate of 50.42%， and the flotation concentrate contains 35.75 g/t of gold， and the gold recovery rate of 41.57% were obtained. The total recovery rate of the gold in the whole process reached 91.99%， which well completed the recovery of the gold in the mine.

Key words: native gold, Knelson gravity concentration, liquid water, gravity multiples, flotation