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Modelling dewatering behaviour through an understanding of solids formation processes. Part I--Solids formation
A C Dustan1, B Cohen, J G Petrie
1Department of Chemical Engineering, University of Cape Town, Rondebosch, 7700, South Africa.
Advances in Colloid and Interface Science
|June 7, 2005
Summary
A new model explains how solids form during precipitation, linking formation mechanisms to particle characteristics and dewatering behavior. This research on nickel hydroxide precipitation offers insights into solid formation processes.
Area of Science:
- Chemical Engineering
- Materials Science
- Environmental Science
Background:
- Understanding solids formation is crucial for predicting particle characteristics and dewatering behavior.
- Current models often lack detailed consideration of hydrodynamics and spatially variant conditions.
- Accurate prediction of solid properties impacts downstream processes like filtration.
Purpose of the Study:
- To propose and validate a comprehensive model for solids formation during precipitation.
- To link precipitation hydrodynamics and solution chemistry to the kinetics of nucleation, growth, and aggregation.
- To investigate the impact of model predictions on dewatering and filtration behavior.
Main Methods:
- Developed a reactant mixing model based on precipitation vessel hydrodynamics.
- Utilized equilibrium speciation and adsorption models to quantify solution conditions.
- Employed empirical kinetics and population balance models to describe particle size evolution.
- Experimentally validated the model using nickel hydroxide precipitation.
Main Results:
- The model successfully captures the evolution of particle sizes during nickel hydroxide precipitation.
- Spatially variant supersaturation profiles were found to be key drivers of solids formation kinetics.
- Model predictions showed good agreement with experimental data, highlighting the importance of hydrodynamics and adsorption.
- Identified limitations due to computational simplifications and data gaps.
Conclusions:
- The proposed model provides a robust framework for understanding and predicting solids formation.
- Accurate modeling of solids formation is essential for optimizing dewatering and filtration processes.
- Further refinement of the model can be achieved by addressing computational constraints and incorporating more detailed kinetic information.