Resource recovery

Circular economy (CE) is a paradigm shift proposing “a regenerative system in which resource input and waste, emission, and energy leakage are minimized by slowing, closing, and narrowing material and energy loops” (Geissdoerfer et al., 2017). From a post-production perspective, CE attempts to recover and reuse part of the raw materials and energy employed in the production cycles, unlike its Linear Economy counterpart which is based on the obsolete mode of production that disposes of the waste generated at the end of the cycle. This new approach attempts to transform the industrial system to a sustainable basis, thus considering the waste as an unexploited resource/secondary material.

Geissdoerfer M, Savaget P, Bocken NMP, Hultink EJ. The Circular Economy – A new sustainability paradigm? J. Clean. Prod., 2017; 143:757-768.

Our focus is to recover valuable minerals from high-strength industrial effluents. Among this minerals, barium sulfate (BaSO4, barite) is listed as a critical raw material (CRM) by many countries and unions (e.g. European Union). Over 70% of its current usage goes to oil and gas industry.

In a recent publication (Staicu et al., 2020) we showed that high-purity barite can be recovered from industrial effluents, achieving both resource recovery and water treatment. Coal-fired power facilities generate a polymetallic effluent (Flue Gas Desulfurization—FGD) rich in sulfate. FGD effluents may be considered an important secondary resource. This paper investigates the recovery of sulfate as barite (BaSO4), a mineral with high commercial value and a critical raw material. Using equimolar BaCl2, >99% desulfurization of an FGD effluent produced by a coal-fired power plant operating in central Poland was achieved, yielding up to 16.5 kg high purity barite m−3 (Figure 1). The recovered barite was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric (TGA), scanning electron microscopy analysis (SEM), surface properties (PZC), density, and chemical stability (TCLP), and was compared with a commercial reference material. Barite recovery also led to the reduction in concentration of Al (86%), Cu (52%), K (69%), Mo (62%), Se (40%), Sr (91%), and U (75%) initially present in the FGD effluent. TCLP results indicate the entrapment and the stabilization of ~70% Se and ~90% Al in the barite structure. Based on this dataset, an in-depth characterization of the recovered barite is presented, and the removal mechanism of the elements is discussed. The study also provides a preliminary cost benefit analysis of the process. To our best knowledge, this is the first work showing barite recovery and metal removal from FGD effluents using a one-step process (Figure 2).

Staicu LC, Bajda T, Drewniak L, Charlet L. Power Generation: Feedstock for High-Value Sulfate Minerals. Minerals 2020, 10:188. (read me)

Figure 1. Barite recovered from industrial effluents

Figure 2. Diagram of barite recovery and FGD treatment