A proposed process scheme for recovering metal values from pigment manufacturing waste streams

 Effluents from pigment manufacturing operations contain highly toxic substances. These substances in their pure form are highly valuable industrial raw materials and their loss in the effluents is not only a pollution problem but also one implying economic loss. This article describes an approach, which highlights a policy that can allow elimination of a pollution problem with simultaneous economic benefits through recovery of the pollutants in readily marketable forms. This approach converts serious "liabilities into substantial assets" and is worth adopting in many cases. The case considered here is that of the effluent from a plant manufacturing the pigment, phthalocyanine green (PG). This effluent is highly acidic and contains copper and aluminium in chloride form. There is a serious disposal problem concerning this effluent. The work reported here was focussed on recovering the metal values in this effluent in a form which can be readily marketed. Particularly important is the fact that the aluminium value can be recovered in the form of zeolite 4A, which is an environment friendly additive in modern detergent formulations. Received: 1 July 1998 / Accepted: 30 September 1998