[China Geo University (Beijing)]

Potassium salt is one of the important scarce mineral resources in China. In the past 60 years, finding large-scale potash deposits has been a big problem for the geological science community in China. China potash deposit is based on Quaternary salt lake liquid brine potash deposit, but it lacks huge ancient solid potash deposit. The proven reserves of potash mines in China account for only about 2% of the world's total, and 95% of potash mines are used to produce agricultural potash fertilizer. Due to the lack of artificial solid potassium ore in China, the output of potassium fertilizer is limited and the gap is huge, with 340 million mu of potassium-deficient land in China.

Black powder containing potassium nitrate was made in Song Dynasty, and Chinese farmers used plant ash fertilizer to obtain potassium. During the period of 1940, Mr. Yuan Jianqi, a pioneer of salt geology in China, began to pay attention to the clues of potassium salt when he made a preliminary investigation of salt-bearing strata in Sichuan and Yunnan. 1946 Mr. Yuan mentioned in the article "Introduction to Northwest Salt Mines": "In the mother liquor of Chaka (Salt Lake), the existence of potassium has been confirmed, but its composition has not yet been determined. Can you use it? Potassium detection is an important raw material for the manufacture of potash fertilizer and explosives, and it has not been found in large numbers in China, so it is particularly appropriate to pay special attention to it. " From Mr. Yuan's emphasis on finding potassium to the official start of finding potassium after the founding of New China, China has gone through more than 60 years of searching for potassium. It can be roughly divided into three stages in time, namely, the first stage is 1949 ~ 1977, the second stage is 1978 ~ 1999, and the third stage is from 2000 to now.

The first stage (1949 ~ 1977)

1. Potash ore was first discovered in China.

195 1 Professor Ge Fuxiang from the Department of Chemistry of Lanzhou University wrote to the Central Committee, asking for an investigation of salt lake resources in Qinghai. 1956, the "China 12 National Major Science and Technology Long-term Plan" formulated by China government and scientists included the investigation of China Salt Lake. 1957, the China Academy of Sciences and the National Comprehensive Investigation Committee formed the "Salt Lake Scientific Investigation Team of China Academy of Sciences", which defined the main tasks of searching for potassium and boron.

During the period of 1955 ~ 1956, the highway bureau of Qinghai Provincial Communications Department discovered the world-famous Chaerhan dry salt flat when building Dunge Highway in Chaerhan area to cross the Qaidam Basin. After digging a pit to get salt to eat, road builders found that there was inedible bitter and spicy salt, which was sent to Team 632 of Northwest Geological Bureau of the Ministry of Geology for testing and confirmed to contain KCl. Geologist Zhu Xia pointed out that Chaerhan is a huge salt reservoir, and its salt layer contains 0.40% potassium. Therefore, in 1956, the Bureau of Geology and Mining of the Ministry of Chemical Industry, under the instruction of Li Yueyan, the chief engineer of the Ministry, sent Zheng Mianping to Dachaidan, Mahai, Chaerhan and other places to test the potassium content in the intercrystalline brine of Chaerhan Salt Lake, pointing out that there is great hope for finding potassium. Liu Gang, a researcher from Institute of Chemistry, Chinese Academy of Sciences, led a salt lake expedition team with Professor Yuan Jianqi from Beijing Institute of Geology and Han Shenshi, director of the Comprehensive Investigation Committee of China Academy of Sciences as vice captains, and was ordered to go to Chaerhan, Qinghai again on 1957. During this period, Zheng Mianping and Gao Shiyang discovered and identified carnallite minerals and carnallite potassium deposits in Chaerhan halogen pit. Since then, the history of potash fertilizer in China has turned a new page. The following autumn, 5000 young people from more than 20 nationalities produced the first batch of 953t potash fertilizer containing 50% KCl by indigenous method on the boundless and inaccessible Chaerhan Salt Beach. At this time, it was later than Germany 1860 100, the earliest mining of potassium salt in the world.

2. The discovery of ancient potash deposits

1962, a red non-edible potash deposit was discovered in Simao, Yunnan, China, and the team of Yunnan Geological Bureau 16 in Laoyan Cave, Ye Meng, which became the first medium-sized ancient solid potash deposit discovered in China. In order to strengthen the prospecting for potassium, 1962 established the potash geological team of Sichuan Geological Bureau (1964 was renamed as 2 10 geological team, and 1968 was also called the Seventh General Survey and Exploration Brigade, and now it is renamed as the Second Geological Brigade of Southwest Petroleum Geological Bureau). In the early stage, the team mainly engaged in exploration and evaluation of Cretaceous-Paleogene, North China Ordovician, Sichuan Cambrian and Triassic potash deposits, and exploration and evaluation of salt and brine mines. It is considered that the prospect of finding large-scale potash deposits within 3000 meters is not good, but the exploitation and evaluation of Triassic potassium-rich brine resources in the basin is extremely high (Lin, 1994), and the potential resources of liquid potassium brine in Sichuan are predicted to be as high as 40%.

Step 3 look for oil and potassium

In the early 1970s, the Ministry of Combustion and Chemical Industry at that time paid attention to oil and gas geology and salt (potassium) exploration. The Institute of Geology of the Geological Bureau of the State Planning Commission and Jianghan Petroleum Exploration Institute discovered the mirabilite potassium salt layer in Jianghan Oilfield, Hubei Province. However, due to the burial of more than 3000m, it is determined that there is no mining value for the time being. From 65438 to 0974, Mr. Yuan Jianqi published three papers, including Genesis of Salt Deposits in Continental Red Bed Basin, which emphasized the possibility of searching for potassium in ancient continental clastic rocks and oil-bearing basins. 1976, Zheng Zhi, a researcher of the Chinese Academy of Geological Sciences, cooperated with Southwest Research Institute of the State Administration of Geology to compile1/40,000 "National potassium prospecting map" and its explanation, which provided a direction for further potassium prospecting in China. From 1950s to 1970s, many large foreign potash mines were discovered in general survey and oil exploration. At the same time, China is also paying attention to the exploration of potassium in oil exploration. For example, 1977, Petrochemical Press published the book "Methods for Finding Potash Ore in Petroleum Exploration". However, due to the constraints of system division, the future work of "exploring both oil and salt" is not ideal. During this period, a number of books and periodicals, such as Potash Deposit, Potash Ore Collection and Selected Materials, were published internally, which were supplied to potassium seekers all over the country in time to prepare conditions for the next stage of potassium exploration. From 1958 to 1978, only a few potassium salt deposits were discovered by the State Geological Bureau, with KCl reserves less than 200 million t. Compared with foreign countries, potassium resources in China are seriously insufficient, and salt lake brine potassium salt deposits are the main ones. Due to backward technology and lack of resources, the output of potash fertilizer in China only reached 23,000 t in 1978, which was far from meeting the demand of increasing agricultural production and the difficulty of potassium shortage in land year by year. At this time, all parts of the country, especially the southern provinces, have carried out the production of kiln ash potash fertilizer and the trial use of farmland. In order to improve the self-sufficiency rate of potash fertilizer, the State Planning Commission issued a notice in 1975 to plan the development of Qarhan Salt Lake in Qinghai. 1In August 1998, ten ministries and commissions, including the State Planning Commission and the Ministry of Chemical Industry, completed the development planning report, proposing that the annual output of the first phase of potash fertilizer project is 200,000 tons, and that of the second phase is 800,000 tons, which shows that the China government and the older generation of potash fertilizer scientists attach great importance to the development and production of potash fertilizer. Generally speaking, the characteristics of the first stage of the development of China potash industry are: with the concern and participation of the China government and the older generation of potash scientists, the geological survey and scientific research of salt mines focusing on finding potassium and boron were carried out nationwide, and a breakthrough was made in finding potassium, including potassium, boron, lithium, rubidium, cesium, halite, trona, mirabilite, gypsum, sodium nitrate and celestite. China has formed a number of exploration and research forces in different systems, such as geology, chemical industry, Chinese Academy of Geological Sciences, China Academy of Sciences and petroleum, and achieved breakthroughs in potash and potash mines in China. But the work at this stage is far from meeting the needs of agriculture. During the same period, many large-scale marine potash deposits were discovered all over the world.

The second stage (1978 ~ 1999)

1976 The Ministry of Chemical Industry established the Institute of Chemical Mine Geology, which was later changed to the Institute of Mineral Geology, and a potash laboratory was established in it. 1979 the establishment of the "potash geological exploration brigade" under the Ministry of chemical industry in Shandong shows that the Ministry of chemical industry attaches importance to the construction of potash exploration research team. At the same time, in 1979, the State Geological Bureau established the third geological brigade in Yanzhou, Shandong Province, focusing on potassium prospecting. At the same time, the two departments set up a potassium prospecting team in Shandong, which showed the determination of people to explore potassium salt in the eastern part of China, that is, the Ordovician in Shanxi and Shaanxi and the Paleogene basins in Shandong, Jiangsu, Henan and Anhui.

1980, Mr. Yuan Jianqi published "Some Issues on Metallogenic Theory of Potash Deposits", and put forward the concept of continental salt-potassium metallogenic model of "high mountain and deep basin" for the first time. 1983 perfected the theory and published "Analysis of a new model of salt formation in alpine deep basins", which enriched the theory of continental salt potassium salt formation. 1984 national conference on salt accumulation was held in Xining, Qinghai. In order to quickly change the serious shortage of potassium resources in China, the Ministry of Geology and Minerals arranged the general survey of Paleogene and Quaternary potassium resources in the western and northern Qaidam Basin in China from 1985 in the seventh five-year plan. In addition to completing the ground investigation, the new technology of airborne gamma-ray spectrometry is also used for remote sensing to find potassium.

1995 10 A brine potash mine was discovered in Luobei depression by the special group of "Potassium Formation in Lop Nur Prospecting Area" led by Wang Youli, Institute of Mineral Deposits, Academy of Geological Sciences. From 1995 to 1999, the Ninth Five-Year Plan research group, led by the deposit of the Chinese Academy of Geological Sciences and attended by the Second Geological Brigade of the Xinjiang Bureau of Geology and Mineral Resources and the Remote Sensing Center of the Ministry of Geology and Mineral Resources, braved the harsh climatic conditions of the "sea of death" and relied on the determination to find a large potash mine for the country and the people with simple equipment, willing to endure hardships and overcome many difficulties with wisdom. According to the controlled area, coal seam thickness and average grade, the exposed geological reserves of KCI brine in the potash deposit in Luobei sag have exceeded 250 million t, reaching a large or extra-large scale. Potash fertilizer in China Salt Lake has grown from scratch, and the amount of K20 resources is about 500 million tons.

The third stage (2000 ~ 20 1 1)

On August 20 10, the "973" national key basic research project of potassium salt "Study on formation law and prediction of marine potassium in China landmass" declared by Salt Lake Research Center of Chinese Academy of Geological Sciences and Institute of Mineral Resources was approved by the Ministry of Science and Technology.

This project is the first joint action of China's research team looking for potassium, which has realized the dream of searching for potassium for generations in China. China has been searching for potassium for 60 years, and the discovered potash resources can only meet about 30% of domestic demand, while 70% of agricultural potash consumption still depends on imports. Therefore, potassium salt is one of the important strategic mineral resources related to the stable increase of grain production in China. In order to reverse the bottleneck problem of potassium prospecting in China, Academician Yuan Jianqi clearly pointed out as early as 1988 that "the focus of potassium prospecting should also be shifted to marine strata". The ideal of searching for potassium in marine strata in China, which was put forward by Academician Yuan Jianqi in his later years, was finally taken seriously by the state after 20 years, and was realized through the "973" project plan.

Under the direct leadership, organization and coordination of the Science and Technology Department of the Ministry of Land and Resources and the China Geological Survey, and with the joint recommendation of the Ministry of Land and Resources, the China Geological Survey, the China Academy of Sciences and Qinghai Province, researcher Liu Chenglin of the Institute of Mineral Resources of the Chinese Academy of Geological Sciences served as the chief scientist of the project, and academician Zheng Mianping of the Institute of Resources of the Chinese Academy of Geological Sciences served as the head of the expert advisory group.

The project also includes the Qinghai-Tibet Plateau Research Institute of China Academy of Sciences and the Exploration and Development Research Institute of China Petroleum and Natural Gas Co., Ltd. More than 30 young and middle-aged scholars, 90% of whom are doctors, will directly participate in the research of the project. It is estimated that the project will be completed in five years from 20 1 1 to 20 15. Scientific potassium prospecting is the core of this project, and the research on potassium prospecting will be quantitative, directional and localized, which will be the successful way for China to find potassium. At the same time, under the guidance of going abroad and seeking international development and utilization of potash resources, many enterprises in China set up forces to carry out geological exploration and mine construction of potash deposits in Thailand, Laos, Canada, Congo and other countries.

refer to

[1] Yuan Jianqi. Introduction of northwest salt mine. See: Selected Papers of Professor Yuan Jianqi on Salt Geology. Beijing: Academy Press, 1989.

[2] Rich is strong. Commemorating the 40th anniversary of the discovery of potassium salt in China. Chemical mineral geology, 1996,18 (4): 314 ~ 316.

[3] Academician Zhang Pengxi introduced. Salt Lake Research,1997,5 (3 ~ 4):120 ~122.

Zheng Jinping, wait. Qinghai-Tibet Plateau Salt Lake. Beijing: Science and Technology Press, 1989.

Qu Yihua, Cai Keqin, et al. Regularity and prediction of potash mineralization in Lanping-Simao basin. Beijing: Geological Publishing House, 1998.

Lin. Discussion on liquid potassium mineral resources and its development in Sichuan basin. Chemical Geology, 1994, 16(2)

[7] Zhang Wusheng et al. Geology and Mineral Resources of Qinghai. Xining: Qinghai People's Publishing House, 199 1

[8] Meng Qing. Salt-forming geological conditions and potassium prospecting prospect of Ordovician in northern Shaanxi. Chemical mineral geology, 1996, 18( 1)

[9] Yuan Jianqi. Letter from Professor Yuan Jianqi to Minister Qin Zhongda. Chemical mineral geology, 1996, 18(4)

Hu Dongsheng, Li Tingqi. Remote sensing geological study on potash mineralization prospect in Lop Nur area. Salt Lake Geology, 1988(4)

[1 1] Liu Xidun. Lop Nur is expected to become the largest producer of potassium sulfate in China. Science and Technology Daily,1997-01-18 (1).

[12] Zhang Pengxi. Genesis of ancient abnormal potassic evaporite. Beijing: Science Press, 1993.

[13] Yuan Jianqi, Yang Qian, et al. Formation conditions of potash deposit in Chaerhan Salt Lake. Beijing: Geological Publishing House, 1995.

[14] Yang Qian, Wu Bihao, et al. Geology of potash deposit in Chaerhan Salt Lake. Beijing: Geological Publishing House, 1993.