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Heptahydrate crystal and preparation method

A technology of zinc sulfate heptahydrate and crystals, which is applied in the field of waste water resource treatment, can solve problems such as complex production process, low product purity, and poor thermal stability, and achieve simple and easy-to-control operating conditions, smooth crystal surface, and good thermal stability Effect

Active Publication Date: 2016-01-27
CHINA TIANCHEN ENG +1
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Problems solved by technology

Patent CN102515254B proposes four steps to realize the conversion of zinc sulfate solution into zinc sulfate heptahydrate crystals, which also ignores the regulation of crystal morphology indicators, and ignores the influence of macroscopic morphology, purity and metal impurity ion content of crystal products on the quality of crystal products
Feng Lin and others studied the thermodynamic stability of zinc sulfate heptahydrate produced by Chongqing Beibei Chemical Reagent Factory in "A Preliminary Study on the Dehydration Mechanism of Zinc Sulfate Heptahydrate Thermodynamics" (Journal of Chongqing Normal University, 2006, 3, 55-57). It shows that the dehydration process of zinc sulfate heptahydrate is divided into three steps, one molecule of crystal water will be lost at 41.5°C, and the seven molecules of crystal water will be completely lost at 253.6°C, and its thermal stability is poor
[0004] It can be seen from the above existing methods that the domestic technical level of extracting and refining zinc sulfate heptahydrate is still low, and the production process is relatively complicated, ignoring the regulation of crystal morphology indicators
Through experimental verification, the zinc sulfate heptahydrate product agglomeration of current domestic process production is serious (see figure 1 ), the degree of crystallinity is low, there is no obvious crystal habit, the purity of the product is low, and the content of metal impurity ions seriously exceeds the standard (see Table 1). At the same time, the thermal stability of the product is poor, which is not conducive to the storage, transportation and use of the product

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  • Heptahydrate crystal and preparation method
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  • Heptahydrate crystal and preparation method

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Embodiment 1

[0033]Weigh 200.0 g of a binary solvent of methanol and ultrapure water, and the mass fraction of methanol is 20%. Add refined concentrated sulfuric acid dropwise, the mass ratio of sulfuric acid to binary solvent is 0.5:1; according to the molar ratio of zinc source and sulfuric acid as 1:1, add zinc carbonate three times, the reaction temperature is 50°C, and the reaction time is 30min; Add refined concentrated sulfuric acid, the molar ratio of zinc source to sulfuric acid is 1:0.25, and react for 30 minutes; lower the temperature of the solution to 5.0°C at a cooling rate of 0.2°C / min, and keep the temperature constant for 30 minutes; Pure water binary solvent (w methanol = 20%) is used as detergent to wash the filter cake, and the volume ratio of detergent to initial methanol and ultrapure water binary solvent (200.0g) is 0.5:1; The obtained filter cake is dried under 0.08MPa to obtain 264.74g of prismatic zinc sulfate heptahydrate crystals, the purity is 99.8%, and the yi...

Embodiment 2

[0035] Weigh 200.0 g of a binary solvent of ethanol and ultrapure water, and the mass fraction of ethanol is 50%. Add refined concentrated sulfuric acid dropwise, the mass ratio of sulfuric acid to binary solvent is 0.2:1; according to the molar ratio of zinc source and sulfuric acid as 1:1, add zinc oxide three times, the reaction temperature is 60°C, and the reaction time is 10 minutes; Add refined concentrated sulfuric acid, the molar ratio of zinc source and sulfuric acid is 1:0.05, and react for 30 minutes; lower the temperature of the solution to 10.0°C at a cooling rate of 0.5°C / min, and keep the temperature constant for 60 minutes; suction filter the suspension, and use ethanol and super Pure water binary solvent (w ethanol=50%) is used as detergent to wash the filter cake, and the volume ratio of detergent to initial methanol and ultrapure water binary solvent (200.0g) is 0.5:1; The obtained filter cake was dried under 0.10MPa to obtain 106.58g of prismatic zinc sulfa...

Embodiment 3

[0037] Weigh 200.0 g of a binary solvent of isopropanol and ultrapure water, and the mass fraction of isopropanol is 35%. Add refined concentrated sulfuric acid dropwise, the mass ratio of sulfuric acid to binary solvent is 0.3:1; add the binary mixture of zinc oxide and zinc hydroxide three times according to the molar ratio of zinc source to sulfuric acid as 1:1 (molar ratio is 1: 1), the reaction temperature is 55°C, and the reaction time is 20min; add refined concentrated sulfuric acid for the second time, the molar ratio of zinc source to sulfuric acid is 1:0.10, and react for 20min; the solution is reduced to 5.0°C at a cooling rate of 1.0°C / min ℃, constant temperature for 60min; the suspension was filtered with suction, and the filter cake was washed with a binary solvent of isopropanol and ultrapure water (w isopropanol=35%), and the detergent was mixed with the initial methanol and ultrapure water. The volume ratio of the primary solvent (200.0g) was 0.5:1; the result...

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Abstract

The invention provides a heptahydrate crystal and a preparation method. The preparation method includes the following steps that 1, sulfuric acid is dissolved in reaction liquid, and the reaction liquid is binary solvent and / or crystallization mother liquor of alcohol and water; 2, a zinc source is added, the molar ratio of the zinc source to sulfuric acid is controlled to be 1:1+ / -0.1), and a reaction is conducted for a certain time; 3, sulfuric acid is supplemented, the molar ratio of the supplemented sulfuric acid and the zinc source added in step 2 is controlled to be (0.05-0.25):1, and the reaction is continued for a certain time; 4, after the reaction is ended, a solution is cooled and separated, the separated solid is subjected to postprocessing, and a product of the heptahydrate crystal is obtained. The product of the heptahydrate crystal has obvious prism-shaped crystallization habit, and dewatering endothermic peaks exist at the temperature of 75+ / -1 DGE C, the temperature of 103 + / -1DEG C, the temperature of 124+ / -1 DEG C and the temperature of 276+ / -1 DEG C of a differential scanning calorimetric curve.

Description

technical field [0001] The invention belongs to the technical field of wastewater resource treatment, and in particular relates to a crystallization and separation method for ammonia nitrogen in ammonia-exchange wastewater, and is especially suitable for the treatment of ammonia-exchange wastewater by SAPO molecular sieves. Background technique [0002] Zinc Sulfate Heptahydrate, also known as Zinc Sulfate and Haolum, the English name is ZincSulfateHeptahydrated, and the molecular formula is ZnSO 4 ·7H 2 O, the molar mass is 287.54g / mol, and the CAS number is 7446-20-0. Zinc sulfate heptahydrate is a very important industrial raw material, widely used in chemical industry, medicine, agriculture, electrolysis, electroplating and other fields. Zinc sulfate heptahydrate is the main raw material for the production of zinc salt and lithopone. It can also be used as a bleaching agent, leather preservative, wood preservative, animal glue clarifying agent, etc.; it is used as an e...

Claims

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Application Information

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IPC IPC(8): C01G9/06
Inventor 杨利强耿玉侠马国栋钱震王志文张媛刘文王亮吕睿李玉龙王曙光王永昌
Owner CHINA TIANCHEN ENG
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