Intensification of flotation separation of carbamide resins from effluent

Abstract

One of the most complex problems arising in the creation of closed water-supply cycles in the refractory industry is the removal from the effluent of finely emulsified organic substances, particularly carbamide (urea-formaldehyde) resin, used as a binder in heat-insulating inserts.To solve such problems, in other branches of industry the flotation method is used [i, 2]. In most cases, before flotation treatment of the effluent coagulants (iron or aluminum sulfate) which promote coagulation of the oily phase and improve the purification conditions, are added to it [3, 4]. This method has serious shortcomings, due to the high consumption (100-120 mg/liter) of the reagents and to the difficulty of subsequent utilization of the separated organic substances.Previously [5, 6] we showed that these shortcomings can be eliminated by adding to the emulsion certain cationic-type surfactants (SUR) instead of inorganic reagents.This article gives the results of developments to establish the possibility of using cationic SUR to intensify flotation separation of carbamide resins from the effluent of refractory undertakings.The investigations were performed on effluent of the Seversk Dolomite Works, formed after compaction of heat-insulating inserts, and on model solutions of KSM-O3P carbamide resin, used in industry.Flotation of the disperse phase of the emulsions was performed in a laboratory machine with mechanical dispersion of air, and a cell capacity of 0.5 liters.The flow rate of air was 540 ml/min.The flotation time needed for the most complete separation of the emulsified resin was 15 min.The resin content of the effluent before and after flotation treatment was determined nephelometrically [7], and from the chemical consumption of oxygen (CCO) [8].The particle size of the disperse phase of the emulsions varied from 40 to 250 ~m. The potential of the particles at pH 7.0-7.5, corresponding to the effluent pH, was 15-20 mV.As cationic SUR --flotation activators --we tried chlorides of quaternary ammonium bases: alkyltrimethylammonium chloride (ATM) and alkylbenzyldimethylammonium chloride (ABDM) with a