(409h) Microfluidic Leaching of K-Feldspar Ore

Microfluidic devices are emerging as a promising tool to intensify throughput and yield of chemical processes. These devices offer the possibility to operate with laminar hydrodynamics, high surface‑to‑volume ratios and small quantities of chemicals. Furthermore, they have the potential for parallelization and integration of several unit operations on a compact and optimized platform, the “lab‑on‑a‑chip”, which minimizes environmental footprint and chemical waste.

In this contribution we present a novel microfluidic device, which is used to investigate the acidic leaching of K⁺ ions from the surface of a K‑feldspar ore (syenite). Syenite is an insoluble material that leaches K⁺ ions at a rate of 10^‑10 to 10^‑14 mol m^-2 s^-1, therefore too slow to be considered as a potassium fertilizer of agricultural soils. Here, we demonstrate that for short times, the leaching rate of K⁺ ions in microfluidic conditions is enhanced (up to 1,000 times faster) with respect to that one obtained from conventional benchtop apparatuses. Such an enhancement can be regulated by adjusting the flow rate in the device. Since the pore network of the soil behaves as a microfluidic system, we demonstrate that in those tropical countries where traditional soluble fertilizers (e.g., sylvinite) cannot be afforded for, insoluble K‑feldspar ores might be a feasible and environmentally sound alternative.