Coal gangue, an industrial solid waste discarded from coal mining and processing, was used as the sole raw material to prepare brick. The coal gangue was crushed, homogenized, milled and then pressed into green compacts. The dried compacts were sintered at different temperatures for 2 h. The obtained brick samples were characterized with X-ray diffraction, scanning electron microscopy, and physico-mechanical properties. Results indicate that bricks are composed of glassy phase, crystals of quartz, mullite, cordierite, as well as pores. The phase components, microstructure, and physico-mechanical properties of the bricks vary significantly with the sintering temperature. The linear shrinkage, bulk density, compressive strength, and flexural strength increase gradually with the sintering temperature enhancing from 900 to 1100 °C, and rise sharply to the maximums at 1200 °C, then drop considerably at 1250 °C. The water absorption value exhibits an opposite tendency. Bricks meeting the Chinese Standard GB 5101-2003 were sintered at 1100–1250 °C. The brick sintered at 1200 °C possesses the optimal properties, with the water absorption and compressive strength values of 3.65 % and 45.61 MPa, respectively. The radioactivity index and leaching toxicity of sintered bricks prepared under the optimum condition were all below the corresponding standards.

Kaolinite nanotubes were prepared by intercalation and solvothermal reactions using pristine kaolin as a starting material. Firstly, an intercalation compound of kaolinite/dimethyl sulfoxide was prepared as a precursor. Then, kaolinite/methanol (KM) was achieved by replacing dimethyl sulfoxide with methanol through solvothermal reaction at 100 °C. Dimethyl sulfoxide molecules can be replaced mostly when the reaction time was 2 h, and the intercalation ratio of KM compound reached 97.9% for the reaction time of 24 h. Finally, the kaolinite nanotubes were achieved by the solvothermal reaction of the KM compound and methanol solution of CTAC (1 M) at 100 °C for 24 h. XRD, IR, SEM, and N2 sorption measurements were used to characterize the as-prepared samples. It is found that the kaolinite nanotubes had a specific surface area of 45.44 m2/g. The length of the nanotubes is about 300–2000 nm and the internal diameter and external diameter is about 15–55 nm and 40–80 nm, respectively.

Li4SiO4 was obtained by using quartz powder of different particle sizes (75–180 μm, 45–75 μm, 38–45 μm, and <38 μm) and Li2CO3 as raw materials through a solid-state reaction at 720 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential thermal analysis and thermogravimetry (DTA/TG) were used to examine the sintering behavior and properties of the samples. The results indicated that when the particle size of the quartz powder decreased, the solid-state reaction performed more completely, the content of the Li4SiO4 phase increased, and the size of the grain agglomerates decreased gradually. The enhanced chemical reactivity of the quartz powder with Li2CO3 and the shortened diffusion distance as the quartz size decreases are helpful to the formation of the Li4SiO4 phase. The sorption analysis revealed that the samples synthesized using the quartz powder with smaller particle sizes experienced a more rapid absorption–desorption process with a higher absorption efficiency.

The intercalation compounds of kaolinite/potassium acetate were prepared by grinding and aging mixtures of potassium acetate and kaolinite from coal measures. The techniques of XRD, ICP-AES, IR, DSC, SEM and particle-size distribution analysis were used to characterize the microstructure and stability of the as-obtained intercalation compounds. The basal spacing increased from 0.72 nm for the raw kaolinite to 1.42 nm for the intercalation compound. The intercalation compounds were very stable in the anhydrous ethanol at room temperature, whereas deintercalation occurred when the as-obtained intercalation compounds were treated with water or heated at 296 °C.