Abstract: The flotation circuit of Dongline company is treating an anthracite coal which has the features of being uxtraordinarily high in pulp density,fine in size and high in ash. A comparative test is made on the performance of the composite and HK flotation agents. Test result shows that HK agent is far superior to composite agent in efficiency no matter whetther low-or high-ash concentrate is intended to be produced. With the use of the HK agent,the ash of the concentrate produced is reduced to 11%~20%.This provides a valuable reference for flotation of anthracite in ultrahigh pulp density.