The waste materials in the historical period, especially the waste metal materials, are in short supply in the market. Because tung oil is in short supply in domestic and international markets, there is a great demand at home and abroad, but the output can't keep up, which has been in short supply, leading to a sharp rise in tung oil prices recently. There is a shortage of copper in this country. From June to April this year, the global copper market was short of 42,000 tons.