The Hairpress filter is a self-cleaning machine specially projected for hair recovery in liming and can also be used for filtering other kinds of leather tanning industry emissions or emissions of other industrial processing. The main characteristic of the Hairpress filter, proposed by S.C. Costruzioni Meccaniche, is that of dewatering and compacting the retained material thanks to a system consisting of a rubber cone with a peculiar shape (S.C. patent) that causes a volume reduction and therefore a reduction in the costs of waste disposal.
The Hairpress filter consist of a filtering pipe with semicircular section, structured in very thick stainless steel perforated plate, with a screw scraping the inner surface of the pipe. The material retained by the filtering panel is removed by the screw and driven to pass through the rubber cone where, thanks to the developed pressure, it loses most of retained water. Special brushes on the external side of the screw deeply clean the filtering holes and prevent them from clogging. Then the filtering flow rate is always high and the filtering system maintenance is reduced to the lowest levels. The filter is always equipped with an inner immersion pump, for recycling the filtered liming. Electrical board and control panel are placed on the machine edge.
Hair recovery from liming baths
The non-destructive systems of liming enable a high reduction in the polluting tanning waste materials both for COD (30-50%) and for suspended solids particles (40-60%), ammonia and sulphide. This processing is effective and easily manageable, provided that the waste disposal flow rate of the filtering system is adequate, so that carrying out times can be reduced. The Hairpress filters are characterised by a high treatment flow rate and by simple functioning and installing, that make them adaptable for any situation. The machine can be gravity fed if the drums are placed about 100 – 200 cm from ground or by means of pumping in case of lower height. In both cases the liming is discharged from the drum throughout waste valves, collected by semicircular gutters (S.C. supply) and conveyed to the filter directly or by means of an immersion pump. The filtered liming is re-pumped to the same drum by the inner pump. This processing lasts till the complete hair removal from liming (about 1 hour) . The retained hair is compacted and discharged with a residual humidity of 40-50%.
The same machine can serve several drums in sequence and the hydraulic circuit of drum selection in recycle ca be equipped with manual or automatized valves or with servo-controlled valves.