The third generation of potassium chloride production technology is increasingly mature

In recent years, the domestic potash fertilizer production has been increasing year by year, the import volume is relatively stable, and the domestic supply has better met domestic demand.
However, my country's soluble potassium resources are in short supply, and the current proven reserves do not exceed 1 billion tons.
Resolutely gradually eliminating outdated processes with outdated production capacity, high energy consumption and high pollution is of great significance to the sustainable development of China's potash fertilizer industry.
??? Through nearly 50 years of development, domestic salt lake workers have jointly tackled key problems and solved technical problems such as the conversion of low-grade and difficult-to-mine solid potassium salts, the efficient separation of lean ores, and the recovery of potassium tailings, forming the third generation of chlorine in my country.
The production technology of potash industry has become an important pillar of my country's demand for potash resources.
Domestic potash fertilizer enterprises adopt innovative technologies to realize the comprehensive utilization of potash fertilizer resources.
The future trend of the development of the entire industry is to take the road of product quality and differentiation and conform to the terminal demand.
The shortage of potassium salt stimulates industrial development.
Potassium exists in the form of compounds in nature.
Potassium resources are divided into two categories: soluble potassium resources and insoluble potassium resources according to their solubility in water.
At present, the main raw material for the production of potassium chloride is still soluble potassium resources, but the global distribution of soluble potassium resources is very uneven.
Canada is the world's largest potassium resource country, accounting for 53% of the world's total reserves, and Russia accounts for 22% of the world's total reserves.
? The domestic potash deposits that have been exploited on a large scale mainly include the Qaidam Basin potash deposit in Qinghai and the Lop Nur potash deposit in Xinjiang.
The reserves of these two deposits account for about 96% of the country's total reserves.
The actual annual demand in my country is 9-12 million tons, making it one of the largest potash fertilizer consumer markets in the world.
However, China's potash fertilizer self-sufficiency rate is only about 50%, and a large amount of potash fertilizer is still needed to meet the domestic market demand.
The long-term shortage of potash has ignited the enthusiasm of domestic scientists to accelerate the research and development of innovative potash production technology.
At the recent potash production technology innovation exchange meeting, Professor Song Xingfu, deputy director of the National Engineering Research Center for Comprehensive Utilization of Salt Lake Resources and Professor Song Xingfu from East China University of Science and Technology, once sorted out the development history of domestic potassium chloride production technology.
He introduced: "Domestic potash production mainly uses brine through natural evaporation to produce qualified carnallite mines.
Generally, the content of sodium chloride is 15%-25%, and the content of carnallite is 70%-84%.
The carnallite mine enters the processing area of ​​the factory to remove sodium and magnesium to obtain the product potassium chloride.
According to the method and process combination of the carnallite mine to remove sodium and magnesium, the process of producing potassium chloride from the carnallite mine can be It is divided into salt field recrystallization process, cold decomposition-hot melt crystallization process, cold decomposition-positive flotation process, reverse flotation-cold crystallization process, etc.
" One innovation From "positive flotation" to "reverse flotation" Cold decomposition refers to partial decomposition with water at room temperature, and its "cold" refers to the process of hot melt crystallization.
The basic principle is to use carnallite to partially decompose with water at room temperature.
During the decomposition process, all the magnesium chloride in the carnallite is transferred to the liquid phase as much as possible, and the KCl is dissolved as little as possible.
This is the demagnesization process of carnallite ore.
? The "cold decomposition-positive flotation" process is a traditional domestic production process for potassium chloride.
The device is simple and reliable, and it is the earliest and most widely used.
However, it has disadvantages such as low potassium recovery rate, large fluctuations in grade, and fine product particle size.
The "reverse flotation-cold crystallization" industrial device is the representative of the advanced process of potassium chloride.
Due to the complex composition of the salt lake ore body and the difficulty of separation, China's potash fertilizer industry completed a 1 million tons potassium chloride plant in 2004 after decades of continuous exploration.
It has become a country that masters large-scale reverse flotation-cold crystallization equipment, both at home and abroad.
It has an important impact, making Chaerhan a strategic base for my country's potash fertilizer production.
? Song Xingfu said: "The process of reverse flotation-cold crystallization technology is mainly to evaporate the brine through the primary sodium salt pond, crystallize and separate most of the sodium chloride; then enter the secondary salt field to evaporate and crystallize the crude light containing sodium chloride impurities.
Halite ore: The coarse ore is flotation to obtain refined carnallite ore, and the concentrate enters the cold crystal decomposition equipment to obtain potassium chloride product.
Other components including magnesium chloride enter the liquid phase and are discharged after separation or enter other processing enterprises.
We found After the operation of the device, there are obviously low potassium chloride yields, high consumption of fresh water and natural gas, and other urgent energy-saving, emission-reduction and sustainable development issues that need to be resolved.
Compared with Jordan and Israel, many technical indicators still have a certain gap.
" Sub-optimization overcomes bottlenecks, reduces consumption, saves energy and increases production.
Facing the various shortcomings of the device, the domestic scientific research team has stubbornly embarked on the road of secondary R&D.
Song Xingfu said: "During the research and development process, we discovered the core element that affects the particle size and yield of the product: precise control technology.
At the same time, the mechanism of carnallite decomposition and crystallization of potassium chloride was studied, and a mathematical model related to carnallite decomposition and crystallization was established.
, And further carried out research on dissolution kinetics and enhanced dissolution engineering, optimized and improved the internal configuration of the crystallizer, so that the crystallization operation process conditions were optimized.
"? Facts have proved that by controlling the concentration of magnesium chloride in the cold crystallizer, the fine crystal is strengthened.
Dissolving and reasonable stirring type, the particle size of potassium chloride produced has been greatly increased.
The large-flux, low-shear spiral propeller stirring paddle, which is optimized for the geometric parameter system of the crystallizer based on fluid mechanics analysis, has been successfully applied in practice.
The coarse potassium particle size is greater than 0.
2 mm particles are generally above 85%, and the highest can reach 90%.
Song Xingfu emphasized: “After the optimization of the installation, the natural gas consumption per ton of product has been reduced by 33%, the potassium chloride recovery rate has increased by 5%, the fresh water per ton of product has been saved 0.
4 tons, and the drying energy can be reduced by 33%.
”? Years of development, focusing on technical bottlenecks such as reverse flotation separation of sodium chloride in salt lakes, cold decomposition and crystallization of carnallite, and development of low-grade potassium chloride resources.
Major breakthroughs in equipment and engineering have made my country's potash fertilizer production technology reach the international advanced level.
The increasingly mature third-generation potassium chloride industrial production technology in my country has solved the major strategic needs of the country's potassium resources, supported the sustainable development of the country's potash fertilizer industry, and realized the protective and rational development of my country's salt lake potassium resources.