20    PRESSURE FLOTATION OF NITROCELLULOSE
FINES: HYDRODYNAMICS AND INTERFACIAL
CHEMISTRY
Domenic Grasso, Associate Professor
Environmental Engineering Program and
Department of Civil & Environmental Engineering
The University of Connecticut
Storrs, Connecticut 06269-2037
Paul LaFrance, Project Engineer
CH2M Hill
Denver, Colorado 80222-0508
Byung-Joon Kim, Environmental Engineer
U.S. Army Construction Engineering Laboratory
CECER-EN
Champaign, Illinois 61820-1305
Hsien-Lun Hu, Doctoral Candidate
Environmental Engineering Program
The University of Connecticut
Storrs, Connecticut 06269-2037
INTRODUCTION
The production of nitrocellulose (NC) creates large quantities of waste NC fines in wash water
streams. Current processing techniques attempt to remove these fines by cross-flow microfiltra-
tion, pressure flotation, settling, centrifugation, and lime precipitation. Pressure flotation, or dissolved air flotation (DAF), is a solid/liquid separation process first developed in the ore processing industry. DAF has since found many applications in the environmental engineering field
including: drinking water clarification, sludge thickening, and the clarification of wastewater
from a variety of industrial and municipal processes.
The work presented herein is part of a larger effort to explore techniques to recover and reuse
nitrocellulose (NC) fines resulting from propellant manufacturing processes. Previous papers1-2
investigated NC particle stability and interfacial thermodynamics and developed a flotation trajectory model. This paper builds on that work and presents a sensitivity analysis of the flotation
trajectory model. The sensitivity analysis explores both operational and parameter estimation uncertainty.
MODEL STRUCTURE
The limiting trajectory approach is a quantitative description of particle-deposition rates on
collector surfaces. Flotation efficiency can be predicted by calculating a particle's trajectory
around the surface of a bubble (Figure 1). Trajectory models have also been utilized to describe
other environmental engineering processes, such as coagulation, filtration, and membrane
processes. Surface forces on the particles and bubbles, as well as short range hydrodynamic interactions near the bubble surface must be quantified to accurately predict the particle's trajectory.
50th Purdue Industrial Waste Conference Proceedings. 1995, Ann Arbor Press, Inc., Chelsea, Michigan 48118.
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