Since the 1970s, magnetic separation has been increasingly used for purification of liquid, such as heavy-metal ion removal from laboratory waste-water, purification of kaolin clay in the paper-coating industry, waste water recycling in the steel industry, and recycling of glass grinding sludge in cath- ode-ray tube polishing factories. In the 1980s, large superconducting magnets were adopted for the field coils of high-gradient magnetic separation system used for kaolin clay purification. In this paper some practical aspects of the construction of a matrix high-gradient separator equipped with the DC superconducting electromagnet as well as the problems of working conditions of the separator are presented.