Photo taken on July 18, 2019 shows the production equipment at Lop Nur in Ruoqiang county, northwest China's Xinjiang Uygur Autonomous Region. Lop Nur, the second largest saltwater lake in China, is an important production base of potassium sulfate. (Xinhua/Zhao Ge)

　　Photo taken on July 18, 2019 shows the production equipment at Lop Nur in Ruoqiang county, northwest China's Xinjiang Uygur Autonomous Region. Lop Nur, the second largest saltwater lake in China, is an important production base of potassium sulfate. (Xinhua/Zhao Ge)

　　Aerial photo taken on Aug. 15, 2019 shows sunset at the salt pan at Lop Nur in Ruoqiang county, northwest China's Xinjiang Uygur Autonomous Region. Lop Nur, the second largest saltwater lake in China, is an important production base of potassium sulfate. (Xinhua/Zhao Ge)

　　Aerial photo taken on Aug. 15, 2019 shows the salt pond at Lop Nur in Ruoqiang county, northwest China's Xinjiang Uygur Autonomous Region. Lop Nur, the second largest saltwater lake in China, is an important production base of potassium sulfate. (Xinhua/Zhao Ge)

　　Photo taken on Aug. 14, 2019 shows the sunrise at Lop Nur in Ruoqiang county, northwest China's Xinjiang Uygur Autonomous Region. Lop Nur, the second largest saltwater lake in China, is an important production base of potassium sulfate. (Xinhua/Zhao Ge)