Junxiong Zhan’s research while affiliated with Nanchang Hangkong University and other places

Feldspar beneficiation produces large amounts of slime waste, which should be efficiently recycled to achieve the economic and environmental benefits. In this study, mechanochemically assisted acid leaching (MAL) was employed to efficiently recycle high-grade concentrate powders, and the physically beneficiated powder from feldspar slime was initially used as a feedstock to reduce gangue mineral disturbance. Milling time and leaching parameters were investigated to reveal their effects on the mass recovery and whiteness of concentrate powders, and the purification mechanism was clarified by chemical reactions and leaching kinetics. The colored minerals were partially liberated and removed by the mechanochemical treatment and further reduced by acid leaching. The optimal MAL process consists of 2 h milling of the feedstock powder in the 5% HCl solution and acid leaching at 95 °C for 4 h. When the feldspar slime was beneficiated by the combination of magnetic separation and MAL, the mass recovery of the ultrafine (0.72 μm) concentrate powder was 76.7%, with a grade of 0.10% Fe2O3. The whiteness’s of the powder and the burnt sample were 91.2% and 64.3% respectively. This facile processing route enables commercial recovery of high-grade concentrate powders from feldspar slime, thus promoting sustainable exploitation of feldspar resources. Graphical Abstract

Quarrying and processing of granite produce large amounts of waste residues. Besides being a loss of resources, improper disposal of these wastes results in pollution of the soil, water and air around the dumpsites. The main components of granite waste are quartz, feldspars and a small amount of biotite. Due to its hard and dense texture, high strength, corrosion resistance and wear resistance, granite waste may be recycled into building materials, composite materials and fine ceramics, effectively improving their mechanical properties and durability. By using the flotation process, high value-added products such as potash feldspar and albite may be retrieved from granite waste. Also, granite waste has the potential for application in soil remediation and sewage treatment. This review presents recent advances in granite waste reutilization, and points out the problems associated with its use, and the related countermeasures, indicating the scale of high value-added reutilization of granite waste.

Shellfish aquaculture has developed rapidly, and the annual production of shell waste by-products exceeds 10 million tons. The reutilization of shell waste is a severe problem in terms of environmental protection and the development of the circular economy. Due to its limited economic value, shell waste has generally been discarded or sent to landfill without any further processing and reutilization, thereby wasting resources and severely degrading the coastal ecosystem. This review summarizes recent research into the reutilization of shell waste, including applications in the fields of agriculture, construction, environmental protection, chemical production, food additives and biomaterials. Problems and strategies related to the reutilization of shell waste are analysed in order to provide technical support for the large-scale and high value-added utilization of shell waste.