A kind of method that takes brine as raw material to prepare potassium sulfate

Abstract

The invention discloses a method for preparing potassium sulfate from brine. The method comprises that a borofluoride is added into brine, the mixture undergoes a reaction at the room temperature, the reaction product is filtered so that potassium borofluoride solids are obtained, the filtrate is collected, the potassium borofluoride solids and concentrated sulfuric acid directly undergo a reaction to produce potassium sulfate solids and fluoroboric acid gas, water-soluble quaternary ammonium sulfate is added into the filtrate so that fluoborate ions in the filtrate are transformed into quaternary ammonium cationic borofluoride, the quaternary ammonium cationic borofluoride further reacts with concentrated sulfuric acid to produce fluoroboric acid gas and a water-soluble quaternary ammonium sulfate solution to be recovered, the fluoroboric acid gas obtained by the two steps are respectively absorbed by an absorbent so that the fluoroboric acid gas is transformed into a borofluoride, the reaction solution is concentrated until saturation and the saturated reaction solution is recovered and then is used in a reaction of a borofluoride and brine. The method mainly comprises two steps, has a fast reaction rate and a high conversion rate, has a potassium ion recovery rate of 92% or more, produces a potassium sulfate product with purity of 97-99% and can be directly applied for crops.

Description

technical field [0001] The invention relates to a method for preparing potassium sulfate in the field of inorganic chemical industry, in particular to a method for preparing potassium sulfate by using brine as a raw material. Background technique [0002] Potassium sulfate is an important chlorine-free high-quality potassium fertilizer. It has a low saline-alkali soil index, is suitable for a wide range of crops, and can provide sulfur trace elements. It can not only increase crop yield, but also improve crop quality. However, my country is a country that is relatively deficient in potassium resources, and a large amount of potassium fertilizers are dependent on imports. Therefore, the method for preparing potassium sulfate at a lower cost by using easy-to-obtain raw materials has become a hot spot of current research. [0003] Brine is a kind of water with strong mineralization, including salt lake brine, underground brine, sea salt brine, etc., which contains a lot of mag...

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Problems solved by technology

However, these commonly used precipitants are either toxic and harmful, or expensive or require high reaction conditions during precipitation. For example, dipicrylamine is an explosive and toxic organic solvent, which will cause harm to human health and endanger the environment; perchlorate [1] The price is expensive, the precipitation process must be carried out under low temperature freezing, resulting in high energy consumption, and perchlorate will pollute the environment; gypsum and phosphate [2] The precipitation method requires the use of a large amount of precipitant, resulting in production costs higher than the product value; sodium tetraphenylborate [3] It is a common reagent in analytical chemistry, used for the quantitative detection of potassium ions, rubidium ions, cesium ions, silver ions, thallium ions and ammonium ions. It can form white precipitates with these ions at low temperature, but it is very expensive and cannot be recycled. , will pollute the environment

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