Search results for "pickling proce"
showing 4 items of 4 documents
Diffusion dialysis for HCl and heavy metals separation from highly concentrated pickling solutions
2019
Disposal of pickling waste solutions strongly affects hot-dip galvanizing industries’ economics and environmental footprint. Thus, the recovery of acid is an important step to enhance the process sustainability. Diffusion dialysis (DD) can be used to separate acids and heavy metals (e.g. iron and zinc) from pickling waters, promoting the circular use of such raw materials. In the present work, two DD modules, a laboratory scale unit operating in batch and a continuous operated large unit, equipped with Fumasep anionic exchange membranes were tested. Results obtained show that zinc and iron affect HCl recovery in opposite way, however reaching high recovery values. In particular, zinc consid…
Experimental investigation and modeling of diffusion dialysis for HCl recovery from waste pickling solution
2019
Abstract Hydrochloric acid recovery from pickling solutions was studied by employing a batch diffusion dialysis (DD) laboratory test-rig equipped with Fumasep membranes. The effect of main operating parameters such as HCl concentration (0.1–3 M) and the presence of Fe2+ (up to 150 g/l) was investigated to simulate the system operation with real industrial streams. The variation of HCl, Fe2+ and water flux was identified. When only HCl is present, a recovery efficiency of 100% was reached. In the presence of FeCl2, higher acid recovery efficiencies, up to 150%, were observed due to the so-called “salt effect”, which promotes the passage of acid even against its concentration gradient. A 7% l…
Modeling and Design of Membrane Integrated Processes for HCl and Metals Recovery from Pickling Solutions
2018
Hydrochloric acid pickling is a common practice in steel manufacturing industry. During the process, acid is consumed to dissolve surface oxides and metals are accumulated in the solution. This fact leads to a process efficiency decrease. Continuous regeneration of pickling solutions enhances process rate and performance, but also minimises the highly expensive and environmentally risky wastewater disposal. The recovery of valuable substances (e.g. acid and metals) can be accomplished by coupling diffusion dialysis (DD) and membrane distillation (MD) technologies. In the present work, a steady state process simulator for the integrated process has been developed. The aim is to analyze and p…
DEVELOPMENT AND MODELING OF MEMBRANE PROCESSES FOR THE REGENERATION OF ACID PICKLING SOLUTIONS
2021
The doctoral thesis focuses on a novel integrated process for the recovery and valorisation of acid and metal salts present in the waste solutions of the pickling process. The proposed process is based on the integration of two innovative membrane technologies, the Diffusion Dialysis and the Membrane Distillation, coupled with a reactive precipitation section. This hybrid process allows the recovery and the enhancement of waste solutions, as well as optimal operating conditions for the continuous pickling process, thus improving its efficiency. Hydrochloric acid recovery was assessed through a detailed study on the Diffusion Dialysis process by implementing a wide experimental campaign usin…