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This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 723729.

MD SCHEMATIC IN THE REWACEM ACID PROCESS CHAIN

MD SCHEMATIC TO REGENERATE GOLD BATH

Targets for MD

Concentrate the acid solution coming from

Diffusion Dialysis to target concentration

required in the pickling bath

Demo A

HCl from ~75 g/l ~155 g/l

Demo C, mixed acid

HNO3 from ~89 g/l ~240 g/l

HF from ~29 g/l 31 g/l

Zinc coating (TecnoZinco, Italy) and Stainless Steel production

(DEW, Germany):

PCB manufacturing industry:

An example of the ReWaCEM solution

Design adaptation for ReWaCEM:

1. Decoupling the corrosive feed stream from heating and cooling streams.

2. Major cost reductions for auxiliary equipment such as piping, heating and

cooling circuits do not need to be acid resistant.

3. Waste heat powered, max temperature in heating channel 65 °C

Targets for MD

To regenerate Gold bath in-line by water

evaporation

Demo system will regenerate ~ 2.7 m3/d

Demo D

Au from 5.41 g/l to 5.64 g/l

Cr from 1.67 g/l to 1.74 g/l

Limited max temp. for feed 40 °C

Results and model validation

Good matching of experimental

results and calculations was

observed, which form the basis for

the upscaled prototypes.

Prototype at

SolarSpring GmbH

equipped for all

possible MD -

configurations in the

ReWaCEM project

Membrane distillation for water treatment and resource recovery in the metallurgical industryKirtiraj Chavan, Rebecca Schwantes, Lorenz BauerSolarSpring GmbH, Christaweg 40, 79114 Freiburg, Germany

e-mail: kirtiraj.chavan@solarspring.de, www.solarspring.de

INDUSTRY PROBLEMS AND THE REWACEM SOLUTION

CALCULATIONS AND PROTOYPING FOR UPSCALING

MEMBRANE DISTILLATION – BASICS

Mass-and heat transfer across the hydrophobic

membrane in MD is defined as:

𝐽𝑀𝐷 = 𝐶𝑑𝑝

𝑑𝑇(𝑇1 − 𝑇0)

𝑄𝑀 = 𝐶𝑑𝑝

𝑑𝑇∆𝐻𝑣 +

𝜆𝑀𝛿𝑀

(𝑇1 − 𝑇0)

Mass transfer coefficient 𝐶 represents the superposition

of molecular and Knudsen diffusion and

viscous flow, 𝑑𝑝 is the change in vapour

pressure over change in temperature 𝑑𝑇 , and

𝑇1 and 𝑇0 are the temperatures at the

membrane interfaces.

∆𝐻𝑣 is the latent heat of vaporization, 𝜆𝑀 is the thermal

conductivity and 𝛿𝑀 is the thickness of the

membrane.