Leaching of aluminum from coal spoil by mechanothermal activation

Abstract

The process of activating coal spoil (CS) in order to recover aluminum as a high value product was investigated. The CS was first characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and thermogravimetric analysis-differential scanning calorimetry (TGA-DSC) in order to determine the chemical and mineral compositions of the CS. Then a mechanothermal activation method was adopted to increase the aluminum activity in the coal spoil. Over 95% of the aluminum in the CS could be extracted using this activation method. The mechanothermal activation process promoted the destruction of kaolinite structures and hindered the formation of amorphous γ-Al 2 O 3 . This resulted in a high aluminum leaching activity in the mechanothermally activated CS.

Sulfuric acid leaching of aluminum from activated coal spoil

“…The infrared spectra (Nicolet 6700, Thermo Fisher Scientific, US) of CS and ACS without and with acid leaching treatment using the KBr disk method are shown in Figure 12. The bands at 3695, 3654, 3620, 1114, 1033, 1006, 910, 793, 754, 692 cm 21 are attributed to the kaolinite, whereas the bands at 793, 754 cm 21 , and from 1113 to 925 cm 21 are attributed to quartz [4]. It can be found in Figure 12 that the leaching treatment altered quartz phase in original CS, but it did not change the quartz picks in ACS.…”

“…CS was purchased from Datuhe (Shanxi) Coking and Chemicals and was prepared with a mechanothermal activation method for the subsequent experiments. The Al 2 O 3 accounted for 25.58% of the total weight in CS and 32.52% in activated CS.…”

“…CS is mainly composed of SiO 2 (30-65%) followed by Al 2 O 3 (15-40%). Therefore, CS is considered as an economical source of aluminum [2][3][4][5][6].…”

“…CS requires an activation process before leaching to achieve remarkable improvement in chemical activity, which results in higher aluminum extraction. A mechanothermal activation method was adopted in the previous research and the activated CS used in this article was prepared by that method . Regarding the leaching of aluminum from CS, the acidic method is most frequently used because of its advantage of comprehensive utilization of aluminum and other metals, such as Boron, Gallium, and Vanadium .…”

Removal of ferric ions from aluminum solutions by solvent extraction, Part II: kinetics study

“…Coal spoil (CS) is a by‐product generated during mining, washing, and processing of coal. CS is an economical source of aluminum because of its high Al 2 O 3 content (15–40 wt %) . Although many methods have been proposed for the extraction of aluminum from CS, say hydrochloric acid route and nitric acid route , a sulfuric acid leaching route presents more promising prospects because today's sulfuric acid production is plentiful in China and sulfuric acid could be recovered and reused for the whole process and removal of ferric sulfate from aluminum sulfate by solvent extraction is a key step in the process.…”