Method and system for preparing salt from seawater

Abstract

The invention provides a method and a system for preparing salt from seawater. The method comprises the following steps: pre-treating sweater through a pre-treating technology to obtain pretreated seawater; dehardening the pretreated seawater through adopting a dehardening technology to obtain ED inlet water; concentrating the ED inlet water by adopting an ion membrane through an ion membrane concentration step to obtain ED strong brine and ED light brine; and carrying out evaporative crystallization treatment on the ED strong brine by adopting an evaporative crystallization technology to obtain the salt. The method makes the treatment scale of a subsequent evaporated crystallizer be reduced by 75%, can reduce 20% or above of the total investment, and greatly reduces the evaporation area; and the system can save 60% of the steam consumption, and reduces 40% or above of running energy consumption.

Description

technical field [0001] The invention relates to the field of salt production, in particular to a method and system for producing salt from seawater. Background technique [0002] At present, there are more than 100 countries and regions producing salt in the world, with a total output of about 240 million tons. The main salt-producing countries are China, the United States, Russia, Germany, Canada, the United Kingdom, India, France, Mexico, and Australia. China and the United States are the two largest salt producing countries in the world, accounting for 36% of the global total. There are two main methods of making liquid salt (brine): the salt field method and the multi-effect evaporation method. The salt field method includes steps such as tide collection and brine making, which are greatly affected by the environment. Factors such as seawater salinity, geographical location, rainfall, and evaporation will directly affect the production of brine (liquid salt), while pro...

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Problems solved by technology

[0003] Patent CN200510021859.1 discloses a method for recovering and treating by-product salt in the production process of hydrazine hydrate. The method includes pulping, separation of salt slurry and alkali slurry, treatment steps of salt slurry, treatment steps of alkali slurry and recovery of mother liquor Utilization and other steps, the process is complicated, and the process does not involve the treatment method of phosphorus-containing organic matter

[0004] Patent CN200510031311.5 discloses a process for recycling industrial salts containing amines, phenols, ethers and other volatile or easily decomposed organic impurities. The industrial by-product salts treated by this method can only meet the requirements of industrial salts and cannot meet the requirements of ionic High requirements for salt for membrane caustic soda, and the calcination time is 4 to 10 hours, and the processing cost is high

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