Recovery of Chromium from Slags Leachates by Electrocoagulation and Solid Product Characterization

Abstract

Slags produced in the steelmaking industry could be a source of chromium. Slags contain, depending on different types of slags, between 2 to 5 wt.% of Cr. Roasting of slag with NaOH, followed by subsequent leaching can produce leachates which can be efficiently processed using electrocoagulation (EC). This paper provides results from the EC process optimization for Cr(VI) solutions with initial concentration 1000 mg/L of Cr(VI). Influence of pH, current intensity and NaCl concentration on the efficiency of chromium recovery, energy consumption as well as solid product composition is discussed in detail. Optimum of pH = 6 was chosen for EC processing of Cr leachates as well as current intensities of 0.1–0.5 A because of the higher Cr/Fe ratio in solid product compared to higher current intensities. Results of EC processing of four real leachates of electric arc furnace carbon steel slag (EAFC), electric arc furnace stainless steel slag (EAFS), low carbon ferrochrome slag (LC FeCr) and high carbon ferrochrome slag (HC FeCr) were evaluated. Comparison of the results of four real leachate samples is presented. Obtained final solid product was identified as (Fe0.6 Cr0.4)2O3 and with up to 20% of Cr could be used as source of chromium in the ferrochrome production.

Multi-Step Recycling of BF Slag Heat via Biomass for CO2 Mitigation

“…Slag volume 300 kg/t HM Slag heat 1 1.7 GJ/t slag Slag heat recovery yield 1 42 % Recovered slag heat 1 0.7 GJ/t slag Recovered slag heat 1 0.2 GJ/t HM Energy required for drying and torrefaction 2 1.3 GJ/t WB Torrefaction mass yield wet biomass to torrefied biomass 2 37 % Energy required for drying and torrefaction 2 3.5 GJ/t TB TB producible with recovered slag heat 0.20 t TB /t slag TB producible with recovered slag heat 0.06 t TB /t HM TB producible with recovered slag heat 17 % (t TB /t coke ) 1 Values based on [3]. 2 Values based on [19].…”

“…Industrial utilisation of slag as a lower value secondary mineral source has been established for decades. Current research focuses on, e.g., the recovery of non-ferrous metals such as chromium via leaching [1] and the carbonisation of slags for carbon capture and storage (CCS) [2]. Slag heat recovery has been a well-studied, ongoing research topic for many decades and has the potential to maximise energy efficiency in iron and steel production.…”

A Review of Circular Economy Prospects for Stainless Steelmaking Slags

“…Also, hydrometallurgical treatments afford means for recovery of valuable metals from stainless steelmaking slags. In a European CHROMIC project (Efficient mineral processing and hydrometallurgical recovery of by-product metals from low-grade metal-containing secondary raw materials), a comprehensive characterization of slags and a survey of different potential methods for metals recovery were performed [13,14,[25][26][27][28]. Extraction of Cr has been promoted, e.g., via mechanical or microwave activation, alkaline roasting/leaching, and acid leaching.…”

Production of complex Fe-Si-Mn-Cr ferroalloy using high-ash coal: a sustainable metallurgical approach

“…Integrating these elements into a single alloy significantly enhances their absorption, optimizes deoxidation, and allows for the adjustment of melting temperature and density, thereby facilitating more effective steel and metal alloying. This represents a significant advantage over using individual ferroalloys of these elements, as it ensures a more uniform distribution of alloying elements and improves the quality of the final product [5,6,[14][15][16].…”