PROCESS FOR PREPARING TANNIDES FROM VEGETABLE STOCK Russian patent published in 1999 - IPC

FIELD: manufacture of colorants and tanning agents based on tannides contained in vegetable stock. SUBSTANCE: claimed process is put into effect by extraction of tannides with hot alkali solution at 65-75 C followed by extraction of remaining hot water and concentration of the resulting extract. Production is made waste-free and economical by extraction of tannides and alkali from remaining vegetable stock in pulsating counter-flow vegetable stock-liquid phase motion mode at frequency of Hz, oscillation amplitude of (0.2-0.4)m for (1-1.5)h followed by continuous concentration of extract and alkali extracted from remaining vegetable stock by twenty-fold recirculation through ultrafilter with filtrates recycled to technological process, and remaining vegetable stock for making building materials. EFFECT: waste-free and ecologically pure process for preparing tannides from vegetable stock and economically advantageous process for producing colorants and tanning extracts. 1 dwg, 2 ex