Disc-type press filter and its industrial testing

Abstract

The main disadvantage of conventional suspension filtration is the slowing down of the process due to the increased pressure drop caused by the growth of the sediment on the filter medium. The issue of mechanical pressing of the sediment in the so-called filters with variable chamber which are used relatively recently to reduce the moisture content during filtration of the sediment, has not yet been resolved. The solids are deposited in the form of a sediment on the rising side of the filter medium chamber. One of the promising technologies for the separation of liquid suspensions is filtration by press filters under pressure or vacuum. Disc press filters are efficient economical equipment, in which a high level of automation of production processes is achieved with the help of modern methods. Press filters are in demand at coal preparation plants, and in metallurgical, chemical, food, and construction industries. Specialists of uranium mining companies make every effort to ensure that the filtering equipment, in addition to the above-mentioned characteristics, also has such features as low energy consumption, high productivity, easy controllability, and meets the standards of environmental safety. The article presents the results of industrial tests of mechanized disk press filters under pressure designed for filtration of suspensions, including high viscosity. The tests of the disk press filter were conducted with production suspensions, and phosphate-nitrate suspensions after dissolution of collective uranium chemical concentrate in nitric acid. It is shown that the proposed disk press filter has the following advantages: simplicity and reliability in operation; compactness; cost is less than that of the disk press filter; weight is twice less than that of analogs; all labor-intensive operations are automated; personnel working conditions meet sanitary and hygienic requirements; labor productivity is much higher than when working on a filter press due to the possibility of servicing several apparatus by one worker. The proposed disk filter press has 2,0–2,5 times higher productivity than the standard frame filter press, which allows for a reduction of 3–4 times the time for auxiliary operations. The maximum specific productivity of the filter by filtrate was 0.55 m³/m² per hour. It is noted that in case of necessity, the achieved indicators can be improved by increasing the specific flow rate of washing liquid. Thus, the press filter of the proposed design can be recommended for implementation in uranium mining and processing enterprises in Ukraine. Keywords: suspension, filter, pressure, collective chemical concentrate, economic performance.