Effect of Electrolytic Manganese Residue in Fly Ash-Based Cementitious Material: Hydration Behavior and Microstructure.

Yaguang Wang,Yingtang Xu,Na Zhang,Xiaoming Liu,Yongyu Ren

doi:10.3390/ma14227047

Abstract

Electrolytic manganese residue (EMR) is a solid waste with a main mineralogical composition of gypsum. It is generated in the production of metal manganese by the electrolysis process. In this research, EMR, fly ash, and clinker were blended to make fly ash-based cementitious material (FAC) to investigate the effect of EMR on strength properties, hydration behavior, microstructure, and environmental performance of FAC. XRD, TG, and SEM studied the hydration behavior of FAC. The pore structure and [SiO4] polymerization degree were characterized by MIP and 29Si NMR, respectively. The experimental results indicate that FAC shows excellent mechanical properties when the EMR dosage is 10%. Moderate content of sulfate provided by EMR can promote hydration reaction of FAC, and it shows a denser pore structure and higher [SiO4] polymerization degree in this case. Heavy metal ions derived from EMR can be adsorbed in the hydration products of FAC to obtain better environmental properties. This paper presents an AFt covering model for the case of excessive EMR in FAC, and it importantly provides theoretical support for the recycling of EMR in cementitious materials.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
Electrolytic manganese residue (EMR) is the main kind of solid waste generated in the production of metal manganese by the electrolysis process [1]
The results showed that a proper amount of sulfate could facilitate the reaction of blast furnace slag to produce C-S-H gel and AFt, which makes cementitious material’s internal structure more compact

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Electrolytic manganese residue (EMR) is the main kind of solid waste generated in the production of metal manganese by the electrolysis process [1]. About 6–9 tons of EMR is produced with the production of per ton of manganese [2]. The prime hazardous substances in EMR are ammonia nitrogen (NH3 -N) and manganese ion, leading to serious environmental pollution problems [3,4,5]. Electrolytic manganese plants have used many different methods to dispose of EMR, the environmental pollution problem is still serious [6,7]. Rational recycling and utilization of EMR can alleviate the environmental problems caused by EMR and bring good environmental benefits to society

Methods

Results

Conclusion