Surfactants in Mineral Processing

Uniformity and thickness of surfactant coating on particles in highly concentrated colloidal solutions significantly affect the optical behavior of particulate systems. Diffuse reflectance transmittance of such a system is a result of multiple scattering of incident light within the system. Multiple scattering theories are too complicated to use to study particulate systems treated with surfactant. Mudgett and Richards (1972) have proposed a mathematical technique to handle multiple scattering problems if single scattering parameters are known. In the present study, we have established a computer program to compute single scattering parameters from size and refractive index of particles and plug the data in multiple scattering theoretical expressions. Theoretical analysis is made for particles in a size range up to 500 AU and having different refractive indices. Results show that diffuse reflectance in this range of particle size is highly sensitive to average particle size in the system. Reflectance changes to a magnitude of 30 to 50 percent as average size increases up to 400 A.U. Theoretical computations for polydisperse systems showed that diffuse reflectance increases with an increase in polydispersity in particle sizes. The proposed theoretical aids can be used to study magnitude and uniformity of coating on colloidal particles, if the single scattering parameters are determined using scattering equations for coated spheres. The objective of the present work is to give a thrust to theoretical aid which has vital prospects for the study of three component system, e.g. particle, surfactant and surrounding liquid.