▎ 摘　　要

NOVELTY - Environmentally friendly dustless chalk comprises 10-20 pts. wt. desulfurated ash, 25-35 pts. wt. sodium thiosulfate, 4-12 pts. wt. activated clay, 5-15 pts. wt. titanium pigment, 1-5 pts. wt. pigment, 0.5-2 pts. wt. nano graphene, 1-4 pts. wt. paraffin, 1-4 pts. wt. lecithin and water (balance amount). USE - Used as environmentally friendly dustless chalk. ADVANTAGE - The dustless chalk: ensures fluent and clear writing; has moderate hardness; has no easily flying dust; and contains desulfurated ash, which reduces impact on the environment. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparation of the dustless chalk, comprising (i) mixing desulfurated ash, sodium thiosulfate, activated clay and titanium pigment, adding water and mixing uniformly to obtain slurry, (ii) mixing pigment and water uniformly to obtain color paste, and (iii) mixing remaining raw materials and water, adding the obtained slurry, mixing, adding the obtained color paste, mixing, extruding and molding, and then drying to obtain final product.