EXTRACTION OF IRON OXIDE FROM STEEL ROLLING INDUSTRY SLAG AND DOPING COPPER CHROMATE: A COMPARATIVE STUDY

Abstract

Increasing efforts to address environmental issues related to industrial waste and the consumption of natural resources by industrial activities have become a global issue. Development in all direction includes significant reductions in waste generation through waste prevention, reduction, recycling, and reuse strategies. At the same time, the expansion of industries worldwide requires a considerable amount of pigment for the industries as an input. The project’s main activities were two broad classes; extracting and processing steel slag from steel rolling waste for pigment application. Then,synthetic and extracted iron was doping in the copper chromate pigment to study its colouring properties. In the first part, the iron content of the steel slag was investigated using X-Ray Fluorescence (XRF); then, iron was extracted using sulphuric acid as a leaching agent, the Inductively Coupled Plasma Mass Spectroscopy (ICPMS) were used to investigate the chemicals leached in the liquid solution. Next, the annealing temperature was determined from the thermographic-Differential Thermal analyzer (TG-DTA), and based on the result extracted sample was annealed at 700C, 800C, 900C and 1000C. After annealing the extracted sample, the crystalline property, crystallite and particle size, morphology, optical and colouring properties were investigated using X-Ray Diffraction (XRD), Dynamic Light Scattering (DLS), Field Emission Gun-Scanning Electron Microscopy (FEG-SEM), Ultraviolet-Visible Spectroscopy Near Infrared (UV-VIS NIR) and Commission Internationale de I’Echlarge (CIEL*a*b*). The characterization results indicated that the sample has good crystallinity, and the formation of hematite(𝛼-Fe2O3) crystalline begins at 700C. However, a new crystalline structure with a chemical formula of (Al3Fe15O12) was observed beyond 800C that overlapped with (𝛼-Fe2O3). The overlapping was observed at around 33.3 and 35.8 2 theta on the XRD peak. Moreover, the range of the extracted sample was from nano to micro with some agglomeration. The optical properties indicated a metal-to-ligand charge transfer at 250 nm while metal-to-ligand charge transfer was between 300 and 550nm. In the end, the colouring result becomes in good agreement with brown red and dark red pigment with good agreement with commercial hematite at 800C, with L* = 30.77, a* = 15.46 and b* = 29.76. In the second part of the study, the synthetic and extracted iron oxide were doped in the copper chromate pigment using a solid-state mechanism. In the process, mixing was done using an agate mortar and pestle; then, an attrition mill was used with 1000 rpm was used for 1:30 h. The sample was dried and ground for 30 min and pressed using 1 ton (9964.016 N) into a pellet of 25 mm diameter. The pelleted one was then calcined at 1350C for 3 h to foster the reaction. After calcination, the calcined pellet was ground and sieved in 100 sieve size mesh (#100). In the end, the sample’s crystalline structure, crystallite size, microstrain, morphology, structural, optical, Refractive index, and colouring properties were examined using XRD, SEM with EDS, FTIR, and UV-VIS NIR. The XRD result indicated that a successful spinel pigment was produced in both synthetic and extracted iron-doped copper chromate pigment. At the same time, the particle size distribution becomes reasonably good with spherical particulate formation. In addition, the FTIR confirmed the spinel structure formation, and UV-VIS NIR showed the absorption of all spectra, a confirmation of perfect black. The CIEL*a*b* confirms the achievement of the best pigment with an optimized result at 0.5 weight percentage iron is doped. In the end, all the parameters that contribute to tuning the colour of the pigment and its colouring axis are comparable with the commercial one and have a promising result.