Recovery method for salt crystals in brine refining mother liquor used for salt production

Abstract

The invention discloses a recovery method for salt crystals in brine refining mother liquor used for salt production. The recovery method comprises the following steps: (1) subjecting well brine to raw brine clarification, addition of chemicals for a reaction and refined brine clarification, then carrying out centrifugation with a centrifuge to remove liquid and subjecting salt slurry obtained after centrifugation to thickening; (2) after thickening, subjecting the salt slurry to standing, allowing supernatant to enter a mother liquor tank through overflowing, pumping salt slurry deposited on the bottom of the mother liquor tank into a dissolving barrel, adding water to fully dissolve the deposited salt slurry and carrying out filtering so as to obtain filtered liquid; (3) allowing the filtered liquid to pass through ion exchange resin so as to remove Ca<2+>, Mg<2+> and a part of sulfate ions, then carrying out heating and pressure-reduced evaporation, maintaining temperature and pressure unchanged after occurrence of crystals, and adding a mixed solution of hydrogen peroxide and ethanol for solvating-out; and (4) after solvating-out, carrying out filtering and pumping obtained filtrate into an evaporator for evaporative crystallization so as to form salt crystals. The recovery method saves cost and can increase output worth3, 400, 000 yuan every year on the base of the annual output of 1, 000, 000 tones of a conventional salt-Glauber's salt combined production apparatus; and impurity ions like Ca<2+>, Mg<2+> and SO4<2-> in the recovered salt crystals are substantially removed.

Description

technical field [0001] The invention relates to the technical field of salt making industry, in particular to a method for recovering salt crystals from salt making refined brine mother liquid. Background technique [0002] As a necessity for human survival and one of the most basic raw materials for the chemical industry, salt plays a pivotal role in the daily life of the national economy. my country is one of the countries with the longest history of salt production in the world, and our country is rich in salt resources. Thousands of salt lakes are dotted in Qinghai, Xinjiang, Tibet and other provinces and autonomous regions. In Sichuan, Yunnan, Jiangsu, Shandong, Henan There are abundant mineral salt underground in Huai'an and other provinces, and Huai'an City has the largest salt mine in the world. [0003] Most of the brines of sulfate-type salt mines in my country contain Mg after water mining 2+ , Ca 2+ , SO 4 2- Such as impurity ions, making salt with this brine...

AI Technical Summary

Problems solved by technology

[0004] 1 million tons / year salt and nitric acid co-production unit has a liquid flow rate of about 130m after the coarse salt is centrifuged 3 / h, the amount of salt crystals is about 0.53% (mass fraction), these salt crystals are deposited on the bottom of the pool after entering the refined brine mother liquor pool, and are discharged by the salt slurry pump at the bottom of the pool, which is equivalent to about 6,000 tons of salt in a year The liquid after the crystal is not thrown by centrifugation enters the brine barrel for the next step of brine, but the waste is discharged

Considering the difficulty of recovering these salt crystals, and there is no good solution to the problem of recovery and purification, most of the currently widely used salt and nitrate co-production processes do not consider the recovery of these salt crystals, resulting in a great waste of resources and wealth

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