Technological process for purifying bittern

Abstract

The invention provides a brine purification technical method which comprises that: a first step is that limewater is added into brine so that reaction happens to calcium hydroxide in the limewater and magnesian ion in the brine to generate magnesium hydrate sedimentation, the magnesian ion in the brine is removed, excessive calcium hydroxide is used for causticizing the sodium sulfate in the brine into sodium hydroxide; a second step is that flue gas is put into the brine after the magnesian ion is removed for carrying out reaction between carbon dioxide in the flue gas and the sodium hydroxide causticized in the brine to generate sodium carbonate which reacts with calcium ion in the brine to generate calcium carbonate sedimentation, the calcium ion in the brine is removed; a third step is that slurry produced in the first step and the second step is collected; and a fourth step is that refined brine after being treated by the first step and the second step is recycled. The technical method can reduce the pollution to environment, can save energy, and can reduce the consumption of raw brine and the purification cost of the brine at the same time, thereby conforming to the requirements of the strategy of sustainable development.

Description

1. Technical field [0001] The invention relates to a brine purification process, in particular to a brine purification process for purifying saturated brine containing calcium and magnesium ions by using a lime-glauber's salt-flue gas method. 2. Background technology [0002] In the process of salt production, as the brine temperature increases, substances with smaller crystal particles, such as CaSO 4 , CaCO 3 , Mg(OH) 2 etc., and substances with higher viscosity, such as MgCl 2 , CaCl 2 The increase of the concentration will increase the viscosity of the feed liquid, and the precipitated substances will form calcium carbonate and calcium sulfate during the process of brine transportation, preheating and evaporation, and scale on the transportation pipeline and the heating pipe wall of the evaporation tank. The main hazards after fouling are: (1) After the inner wall of the heating tube is fouled, the heating effect will decrease, and the energy consumption will increas...

AI Technical Summary

Problems solved by technology

The main hazards after fouling are: (1) After the inner wall of the heating tube is fouled, the heating effect will decrease and the energy consumption will increase. In severe cases, it must be shut down for cleaning

According to relevant information, when the scale thickness in the heat exchanger of water-cooling equipment is 2.16mm, the heat transfer coefficient will drop by 51% on average, and the equipment operation efficiency will drop by 50%.

(2) Increase the water flow resistance of the heat exchange system, reduce the brine flow rate, and increase the energy consumption of the circulating pump

(3) Local corrosion or even rupture and perforation will occur in the lower part of the salt deposits, seriously affecting the safe operation of the equipment

(4) The heat exchange system frequently washes tanks during operation, which requires interruption of production operation, increases the energy consumption of circulating pumps and water, and reduces production efficiency

[0003] At present, salt-making enterprises at home and abroad generally adopt the caustic soda-soda brine purification process. This process requires less investment in basic construction and simple process flow, but the purification cost is relatively high. The general treatment cost is about 20 to 40 yuan / ton of salt, and after treatment There is still a small amount of Ca in the brine 2+ , Mg 2+ ions, there are still scaling factors

[0004] Several domestic salt-making enterprises that use caustic soda-soda ash method for brine purification, due to the rise in the price of caustic soda and soda ash, the cost of brine purification has also increased

In addition, general enterprises control the brine purification treatment index calcium and magnesium content to be higher than 15mg / L, and some enterprises reach 40mg / L, and the treatment cost is between 20 and 40 yuan / ton of salt

There are also several soda ash enterprises that use the lime-carbon dioxide brine purification process. The purification cost of this process is relatively high, and it is only applicable to their own industry

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