Verfahren zur Aufarbeitung von lösemittel- und treibmittelhaltigen Waschrückständen

摘要

Processing wash residues (I) contg. solvents and blowing agents (II), esp. residues contg. PVC-contg. paste and solvent, and recovering the solvent; involves (a) distn. with recovery of solvent and at least partial decomposition of (II) followed by (b) conversion of the pasty residue obtd. into a powder by plastification with cooling and stirring. Pref. before stage (a) and/or (b), a substance which improves the sepn. properties of the residue is added, together with water, pref. 0.5-2.0 wt.% Ca and/or Mg stearate and 0.5-2.0 wt.% water; stage (a) involves heating to 135-145 deg.C under normal pressure and then continuing heating at this temp. at 800-900 mbar, and is ended when the temp. of the solvent vapour falls to below 100 deg.C; stage (b) carried out with turbulent stirring; after (a) and (b), the residues from different batches are mixed in a homogenisation stage (c), pref. with addn. of 0.5-2.0 wt.% water and/or ZnO; the residues from (c) are then mixed with residual pastes, esp. coloured PVC plastisols obtd. as prodn. residues, which are pref. first mixed to give large batches with addn. of 0.5-2.0 wt.% water and/or 0.5-2.0 wt.% ZnO; the pulverised residues and/or residual pastes are preheated and extruded, pref. in a multi-stage shear-roller extruder with heating and cooling stages, which is also used for mixing the prod. obtd. from (I) with the residual paste; the off-gas from heating, contg. solvent and (II), and the gaseous decomposition prods. from (II), are passed through a condenser to a post-combustion unit; the prod. is granulated after, extrusion, and the granules are then cooled. USE/ADVANTAGE - The invention enables the above wash residues to be processed to give a re-usable prod. contg. no solvent or blowing agent.