At the invitation of Professor Nie Junsheng, Professor Nan Zhongren, Professor Wang Shengli and Associate Professor Hu Yahu ofthe College of Earth and Environmental Sciences, Lanzhou University, Professor Zhao Baojin of the University of South Africa came to our university for academic visit and exchange. On July 7, 2021, he gave an academic report entitled "Research on mineral mountain environment and hydrochemistry" in room 1009, Guanyun Building, Lanzhou University. The report was presided over by Professor Wang Shengli.

Starting from the geological background and mineral resources distribution of South Africa, Professor Zhao Baojin's report mainly focuses on South Africa's relevant environmental laws and regulations / best operating procedures, geochemical evaluation and mine acid water treatment, environment and acid wastewater of Rand gold mine tailings dam and waste dump in South Africa, oxidation zoning of old gold mine tailings dam, the laboratory methods and geochemical simulation of mine environmental impact research. Taking the tailing dam of Rand gold mine in South Africa as an example, he explained the environmental management of waste dump and the treatment methods of acid wastewater in detail and focused on the analysis of organic treatment of wastewater, He pointed out that the organic matter of agricultural waste can increase the alkalinity of acid wastewater, create reduction conditions, and make heavy metals form sulfides to precipitate or adsorb on wastes or newly generated minerals, so as to reduce the content of heavy metals in wastewater. Professor Zhao Baojin also gave a deep account of the laboratory geochemical simulation of the oxidation zoning of the old gold tailings dam, and described the advantages and disadvantages of static simulation and dynamic simulation in detail.

In the report, Professor Zhao Baojin emphasized that laboratory static and dynamic simulation experiments and geochemical numerical simulation are necessary means for mine environment research, and proposed that organic passive treatment of acid mine wastewater will be an important research direction in the future. He also made it clear that the organic combination of geochemical and microbial chemistry treatment technology of mine waste and acid wastewater is conducive to improving the efficiency of wastewater treatment and will be an innovative research field. In the report of more than two hours, Professor Zhao Baojin has always maintained a full spirit. Through abundant charts and photos and a large number of case studies, he clearly elaborated the theory and ideas of mine environment research, and put forward his own unique opinions combined with the actual problems of Baiyin mine environment in Gansu Province.

After the report, Professor Zhao Baojin had an interactive exchange for nearly an hour with Professor Wang Shengli, Associate Professor Hu Yahu Dr. Zhao Cuicui, and Associate Professor Xu Shenghui and Associate Professor Wang Yan of Lanzhou University of Technology, as well as the postgraduate students. Professor Zhao Baojin exchanged views with teachers and students on the organic treatment mechanism and ideas of mine wastewater, the soilless ecological restoration of Baiyin Mining Area, the treatment of tailing pond in Baiyin Mining Area and the causes of loess. During the exchange, he talked about the importance of micro organisms in the process of mine environmental restoration, and encouraged teachers and students to challenge some classical theories. Teachers and students said that this report will benefit a lot. The experience of mine environment research and restoration in South Africa can provide reference for domestic mine environment research and restoration, and broaden our academic vision.

After the meeting, postgraduate students Ning Xiang, Liu Mengbo and Yang Meng of the College of Earth and Environmental Sciences, Lanzhou University accompanied Professor Zhao Baojin to visit Baiyin Huoyanshan National Mine Park Museum, and inspected the heavy metal pollution of farmland in Baiyin Dongdagou basin and the microbial remediation demonstration field of heavy metal contaminated soil in Lanzhou University. During the inspection, Professor Zhao Baojin put forward some instructive suggestions for relevant scientific research, and pointed out the urgency of ecological damage and environmental pollution control in Baiyin section of the Yellow River Basin and the need to do a good job in ecological protection and high-quality development of the Yellow River Basin.