Method for preparing non-toxic dust-free shell chalk from discarded shells

Abstract

The invention relates to a method for preparing non-toxic dust-free high-quality shell chalk from discarded shells, belonging to the technical field of production of the teaching tool--chalk. The preparation method comprises the following steps: calcining washed shells at a temperature of 850 DEG C for 120 minutes to obtain calcium oxide powder; introducing carbon dioxide and continuing calcination to obtain high-purity calcium carbonate; and mixing diol and water according to a ratio of 1: 40 to form a water-soluble binder, then carrying out molding in a mold, and performing drying to obtainthe high-quality shell chalk. The chalk prepared by using the method effectively reduces chalk dust in the air, does not corrode the skin of teachers' fingers, and protects the health of teachers andstudents.

Description

technical field [0001] The invention relates to a preparation method of chalk, in particular to a preparation method of using discarded shells to make non-toxic and dust-free shell chalk, which belongs to the field of chalk production technology. Background technique [0002] my country has many lakes, vast sea area, and rich shellfish resources, such as oysters, mussels, meretrix meretrix, and snails. With the rapid development of shellfish farming, the annual output has reached tens of millions of tons in recent years. In addition to providing people with delicious meat, shellfish also leave a lot of shell waste for people. Abandoned seashells have caused serious damage to the ecological environment of coastal areas and also affected people's lives. Therefore, the rational use of discarded shells is imminent. We use discarded shells to develop teaching chalk, so as to provide a way to deal with shells in coastal areas of China. [0003] At present, the chalks used in Chi...

AI Technical Summary

Problems solved by technology

[0003] At present, the chalks used in China mainly include ordinary chalk and dust-free chalk. The main components of chalk on the ordinary market are calcium carbonate and calcium sulfate, and some complex chemical reagents are added, and contain a small amount of metal elements such as iron and cadmium. Long-term exposure can cause skin damage

The dust-free chalk on the market is just adding oily substances to the original penny as a binder, and then adding raw materials with a larger proportion to make the chalk dust not easy to scatter, but it is not obvious in practical applications, and it is harmful to teachers and students. respiratory system damage

Images