Burnt Sand Enriches the Soil Again--A Revolution in the Regeneration of Foundry Waste Sand Begins in Tsuchiura (circa 1997)

Burnt Sand Enriches the Soil Again--A Revolution in the Regeneration of Foundry Waste Sand Begins in Tsuchiura (circa 1997)

In the 1990s, the terms "zero-emission society" and "recycling-oriented society" were beginning to permeate policy and industry in Japan, as various industries sought to recycle construction by-products and industrial waste, starting with the 1991 Recycling Law. In 1997, the Kyoto Protocol was about to be adopted, and Japan as a whole was undergoing a major transition toward "waste-free" and "landfill-free" waste management.

Under these circumstances, a private processing plant in Tsuchiura City, Ibaraki Prefecture, developed a technology for recycling waste sand from used molds into porous ceramics by firing it at about 900 degrees Celsius. The casting industry generates a large amount of mold sand used to form products, most of which has conventionally been sent to landfill. Waste sand, which is discharged in the order of several million tons per year, is directly linked to the social problem of insufficient landfill sites, and has been regarded as an industrial byproduct with a large environmental impact.

The innovation of this technology lies in the fact that it is neither incineration nor landfill, but "recycling through thermal conversion. Ceramics made porous by high-temperature firing have excellent water retention and air permeability, and can be used as water purification agents, soil improvement materials, or vegetation base materials for secondary use. In other words, sand, which was once treated as "waste," has now become a valuable "environmental improvement material," a shift in the meaning of materials.

In 1997, this processing technology was attracting attention both inside and outside the industry as a model plant with a monthly processing capacity of 400 tons and the goal of "zero waste sand. In addition, the Ministry of International Trade and Industry (MITI) was cooperating in the technological demonstration, which was positioned as an advanced initiative involving the cooperation of government ministries, businesses, and local governments.

Behind the development of this technology was not merely economic rationality, but also a shift in thinking that the manufacturing industry should fulfill its environmental responsibilities. The value that waste is not merely an aftertreatment target but the "future of materials" itself brought new ethics and possibilities to the classic manufacturing field of foundry.

This quiet technological revolution that began in Tsuchiura was eventually connected to the core ideas of Japan's industrial policy, such as "resource recycling technology" and the "zero emission" concept. Burned sand is returned to the soil and revived as a material that supports water and greenery. There, another poetry of environmental technology quietly breathed.