Investigation of the effect of flocculation and pulp parameters on the performance of vacuum filtration of Moroccan phosphate slurry using novel definitive screening design

Abstract

For the Moroccan phosphate industry, the dewatering of phosphate slurry is significant challenge that has adverse effects on the cost-efficiency of the transportation of phosphate, and the depletion of the water resources. To overcome this challenge, the company is working on developing a flocculation-vacuum filtration system to enhance the dewatering of the phosphate slurry. In this regard, the objective of our study was to evaluate the effect of the flocculation and pulp parameters of the phosphate slurry on the efficiency of the vacuum filtration of the phosphate. The experiments were planned according to a definitive screening design (DSD), by varying the parameters of six input variables and investigating their impact on the humidity of the phosphate cake and the turbidity of the filtrate. The studied factors were the solids rate (\({{\varvec{X}}}_{1}\)), the specific consumption of the flocculant (\({{\varvec{X}}}_{2}\)), the mass concentration of the flocculant (\({{\varvec{X}}}_{3}\)), the viscosity of the flocculant (\({{\varvec{X}}}_{4}\)), the percentage of the fine particles (\({{\varvec{X}}}_{5}\)), and the duration of filtration (\({{\varvec{X}}}_{6}\)). The factors that affect the humidity of the phosphate the most were identified as the viscosity of the flocculant, followed by the duration of filtration and the specific consumption of the flocculant. Due to the useful features of the DSD, a quadratic model for the turbidity of the filtrate was developed and validated. The parameters of the significant factors that minimize the turbidity of the filtrate were defined, allowing for the determination of the conditions for the reduction in the turbidity to below 3 NTU. These findings show promising efficiency of the proposed separation and dewatering process.