Pretreatment of coal mining sludge through sulfation roasting and water leaching for aluminium extraction

Lew, Chia Xin (2024) Pretreatment of coal mining sludge through sulfation roasting and water leaching for aluminium extraction. Final Year Project, UTAR.

Preview

PDF Download (3596Kb) | Preview

Abstract

The current sludge management plan was ineffective and a waste of valuable substances for coal mining sludge. So, the study aimed to examine the characteristics of raw coal mining sludge and propose a suitable purification method for it. Several analytical techniques were used for the characterisation. Thermogravimetric Analysis (TGA) revealed the sludge was thermally stable after 700 ℃ while Brunauer-Emmett-Teller (BET) determined its surface area, pore sizes, and volumes were 44.97 m2/g, 12.42 nm, and 0.09 cm3/g, respectively. Scanning Electron Microscopy (SEM) further showed that the sludge's surface morphology had a slightly porous irregular structure with an uneven flake-like appearance at the outside borders. Corresponding to Energy Dispersive X-ray spectroscopy (EDX) results, which indicated that oxygen, silicon, and aluminium were the major elements present, the flaky structure was identified as silica oxide. Quartz, kaolinite, muscovite, and magnetite were also discovered to be the primary minerals in the sludge via X-ray diffraction (XRD). Moreover, Fourier Transform Infrared (FTIR) identified silicon and aluminium-related functional groups in the sludge. As such, sulfation roasting and water leaching approach was proposed as the separation method to extract the aluminium from coal mining sludge. Six groups of parameter studies were conducted and EDX was used to assess the extraction efficiency. The ideal conditions were defined as 500 °C roasting temperature, 1:2 sludge to ammonium sulphate mass ratio, 90-minute roasting period, 80 °C leaching temperature, 1:10 solid-liquid ratio, and 90-minute leaching time, yielding 93.2 % extraction efficiency of aluminium from sludge. Afterward, SEM-EDX, XRD, and FTIR were used again to characterise the treated coal mining sludge. The sludge's surface morphology got smoother and the flake�like appearance region was much more visible. The primary element also changed to solely silicon and oxygen based on the EDX test. Furthermore, no kaolinite and aluminium-related bond was found in the XRD and FTIR results compared to the previous, suggesting the proposed separation method was effective. As silica oxide is currently the primary constituent in coal mining sludge, it is possible to infer that the treated sludge can be utilised as an active product for other purposes like glass and ceramic ingredients.

Actions (login required)