Experimental and Numerical Investigations on Conductive Drying of Phosphate Washing Waste Clay

Abstract

Morocco is the leading producer of phosphate and its derivatives in the world with a total production of 35 Mt. However, the extraction and the valorization of this mine generate huge quantities of phosphate washing waste clay (PHWWC) that constitute a main environmental and economic concern. To facilitate this waste clay storage and handling, it is necessary to decrease its moisture content that represents 80% of PHWWC. The present paper is devoted to studying the conductive drying of PHWWC. Drying experiments were conducted in a laboratory pilot. Afterwards, the experiment results were implemented in a one-dimensional numerical model of heat and mass transfer in a porous media to identify the drying parameters and performances. It was found that most of the water contained in PHWWC is free water that is removed with a constant drying rate. The volume reduction with a marked cracks phenomenon attained 65% without any significant effect of drying temperature and sample thickness. The effective moisture diffusivity of the PHWWC for a conductive drying process is ranged between 10−9 and 1.1 × 10−8 m2·s−1. The thermal efficiency of the drying system is up to 86%. The results could be used for the purpose of design and scale-up of the industrial dryer based on laboratory-scale experiments.

Optimizing Convective Drying for Efficient Reduction of Phosphate Sludge Moisture: Experimental Investigations and Mathematical Modeling

“…Phosphate waste contains a high percentage of water, reaching 70-80%. Therefore, the most appropriate solution to facilitate transport, storage and recycling is drying which can reduce the waste volume by approximately 65% [2]. This fact makes it easier in terms of storage and handling [3].…”

“…To the best of our knowledge, studies on drying sludge are limited. Berroug et al [2], and Bellaziz et al [34], have worked on conductive drying of PS. Chaanaoui et al [35], have tested a prototype of PS rotary dryer coupled to a parabolic trough collector, but more experimental investigations are needed to bridge existing knowledge gaps in this field.…”

Geopolitical deadlock and phosphate shortfall behind the price hike? Evidence from Moroccan commodity markets

“…Morocco has become the leading phosphorus producer, generating 35 mil. tons a year (Berroug et al 2021). Historically, Florida is the largest global phosphate maker.…”