A new approach of aluminum extraction from drinking water treatment sludge using ammonium sulfate roasting process. (November 2022)

• Record Type: Journal Article
• Authors: Ballou, Ibtissam; Kounbach, Said; Naja, Jamal; Bakher, Zine Elabidine; Laraki, Khalid; Raibi, Fatima; Saadi, Radouan; Kholtei, Sanae
• Is Part Of: Minerals engineering. Volume 189(2022)
• Publication Date: 2022-11
• Subjects: Aluminum extraction -- Sludge -- Drinking water -- Roasting process; Mines and mineral resources -- Periodicals; Ressources minérales -- Périodiques; Mines and mineral resources; Periodicals; Electronic journals; 622
• DOI: 10.1016/j.mineng.2022.107859
• Languages: English
• ISSNs: 0892-6875

Abstract

Highlights: The characterization of water drinking sludge was investigated. Extracting Al from sludge using an effective and ecofriendly method. The mechanism of Al silicate's transformation into Al2 (SO4 )3 has been elucidated. 74 % of Al has been recovered by using the new approach. Abstract: The drinking water treatment based on the coagulation-flocculation process using aluminum sulfate is widely used the whole word. As the effect of this activity, the huge quantities of the drinking water treatment sludge continue to be an environmental issue and needs to be valorized. The purpose of the present work is to investigate the valorization pathway of this sludge by extracting aluminum using ammonium sulfate roasting and hot water leaching at 80 °C as an alternative method to acid leaching which is energetic and cause corrosion problems. Several techniques were used, i.e., Thermogravimetric/Differential thermal (TGA/DTA) analysis, X-ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM), and inductively coupled plasma - optical emission spectrometry (ICP-OES) to approach the reaction mechanism between sludge and ammonium sulfate. This chemical additive promoted the conversion of aluminum and calcium from the primary phases of the sludge, such as calcite (CaCO3 ), nacrite (Al2 Si2 O5 (OH)4 ), and muscovite (KAl2 (AlSi3 )O10 (OH)2 )to form soluble metal sulfates in a temperature range of 400 °C to 600 °C. The parameters affecting the extraction, such as roasting temperature, mass ratio of ammonium sulfate to sludge, and roasting time were studied. A recovery of 74 % was obtained for aluminum under the optimum roasting conditions. The experimental results showed also a good chemical affinity between ammonium sulfate and other elements present in the sludge, such as calcium, magnesium, and manganese. The extraction efficiency of these elements was 88 %, 91 %, and 77 %, respectively. The characterization of the leaching residue showed the presence of silicon at high content (35.8 %) and low contents of calcium (0.64 %), magnesium (0.16 %), aluminum (2.75 %), and manganese (0.05 %), which confirm the efficiency of the developed process.