New Gradient Flotation Technology And Practice For Low Grade Porphyry Copper Ore

China has become the country with the largest import and consumption of copper metal in the world.With the steady and rapid development of China’s economy,the demand for copper metal is increasing day by day,and the shortage of copper resources is prominent.Insufficient supply of resources has become an important problem that restricts the development of national economy.The contradiction is that China’s copper resources,especially low-grade copper resources,have not been developed and utilized reasonably and efficiently.In order to improve the economic and technical indexes of beneficiation and create economic benefits as soon as possible,based on the study of process mineralogy,Anhui Tongguan(Lujiang)Mining Co.,Ltd.Concentration plant,a newly-built copper concentrator,had developed a gradient flotation process suitable for the properties of this low-grade porphyry copper ore was developed through flotation condition test,closed-circuit comparison test and continuous separation expansion test.This test ore is collected from the middle sections of-650 m,-705 m,-770 m and-800 m in Fengtaishan mine section and-800 m in Tongquanshan mine section.The copper mineral in the ore is mainly chalcopyrite,the iron mineral is mainly hematite,followed by magnetite,and other metal sulfide minerals are mainly pyrite.The gangue minerals in the ore are mainly quartz,followed by feldspar minerals such as albite,oligoclase and orthoclase,sericite,illite and chlorite.The particle size of copper sulfide in this ore is mainly medium and fine,and the percentage of copper sulfide in+0.074 mm particle size is 64.86%.The continuous beneficiation test shows that the copper content of the raw ore and the slime degree of gangue have certain influence on the beneficiation index.According to the ore properties,in order to improve the comprehensive utilization rate of resources,four continuous separation tests with different process structures were carried out,including one roughing,three cleaning and two scavenging processes,two-step copper separation process,two-step copper separation optimization process and two-step copper separation-middling regrinding optimization process.The results of small-scale tests and continuous tests with different technological processes show that the gradient flotation process with two-step copper separation and regrinding of middlings has the best separation index.Two-step copper separation-middling regrinding gradient flotation process continuous separation test accumulated copper concentrate grade of 20.22%,copper recovery rate of 89.29%,gold content of 19.46g/t,silver content of 60.56g/t,gold and silver recovery rates of 74.95% and 24.31%respectively;Compared with the process indexes of one roughing,three cleaning and two scavenging,the copper concentrate grade,gold content in copper concentrate and silver content in copper concentrate are 0.57,4.52 and 9.43 percentage points higher,respectively,and the copper recovery rate,gold recovery rate and silver recovery rate are 1.09,1.48 and0.91 percentage points higher.Compared with the traditional middling treatment process,the gradient flotation process of two-step copper separation-middling regrinding gives priority to the flotation of dissociated minerals,which conforms to the principle of floating early.The undissociated minerals are further dissociated by middling regrinding.At the same time,this process can effectively prevent all middling from entering the regrinding system and affecting the sorting index by determining the reasonable middling regrinding.