How Ancient People Made Lime

Lime, also called limestone powder, is a substance used for sterilizing, disinfecting, paving, building and many other purposes, and is one of the important raw materials in ancient building materials and agricultural production. There are several main methods of making quicklime in ancient times:

1. Calcination method. This is the main method of making quicklime. The limestone powder is put into the furnace and grilled at a high temperature, the carbon dioxide in the limestone will be released to form calcium oxide, and finally the quicklime will be obtained. This method requires the use of special stoves, and the firing time and temperature need to be controlled very accurately.

2. Water washing method. The limestone powder is put into the water and stirred, so that it is fully mixed with water, and then filtered out the impurities, and finally get quicklime. This method is relatively simple, but it requires the use of a large amount of water and limestone powder, and at the same time will produce a large amount of waste water.

3. Sulfuric acid method. Mix limestone powder with sulfuric acid to produce calcium sulfate, then add water to decompose it, and finally get quicklime. This method was more common before the 19th century, but was gradually phased out due to the large amount of wastewater and sulfur dioxide gas produced.

In short, the process of making quicklime by the ancients required the use of large quantities of limestone powder and special tools, as well as the need to control the time and temperature of the firing, and the process required a great deal of experience and skill. Although modern industrial technology has made great progress, some traditional production methods are still widely used and inherited.