Method and apparatus for washing sheets of plastic material

A method for washing film and/or sheets of plastic material and for the separation of contaminant substances, comprising the steps of introducing pre-cut soiled pieces of large dimension of the film or sheets of plastic material into a water bath of a washing tank;

• supplying a washing water flow for dragging the soiled plastic pieces into the washing, tank and for continuously replenishing the water bath in the washing tank;
• adjusting a level of the water bath in the washing tank and positioning the outlet edge of a discharging channel below the level of the water bath in the washing tank so that the water flow continuously exits the washing tank through overflow via a front edge of the discharging channel;
• driving a screw stirrer which extends vertically downwardly in the washing tank and is immersed in the water bath for generating intense stirring of the water bath and a continuous upward recirculation of the water bath to separate clean pieces of plastic material from contaminant substances;
• drawing the cleaned pieces of plastic material floating on the water bath along the discharging channel with an endless belt having a rear end in direct communication with a stirring zone of the water;
• and
• advancing and discharging the cleaned plastic pieces by drawing the cleaned plastic pieces, in a floating condition, along the discharging channel by a combined action of pads extending from the endless belt beneath the level of the water bath along the discharging channel;
• overflow of the water flow exiting the washing tank along the discharging channel;
• and
• adjusting an advancement speed of the endless belt to vary the outlet flow rate of the cleaned plastic pieces in the tank in accordance with a degree of contamination of the plastic pieces and the desired degree of cleanliness thereof.