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Method for purifying low-grade natural gypsum or gypsum tailings by recrystallization

A natural gypsum, low-grade technology, applied in the direction of calcium/strontium/barium sulfate, etc., can solve the problems of difficult to completely remove impurity ions, complicated classification methods, unsatisfactory purification effect, etc., and achieve good industrialization prospects and product purity. High, the effect of solving environmental problems and social problems

Inactive Publication Date: 2015-04-22
QINGHAI INST OF SALT LAKES OF CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The crushing and grading methods are complicated in process, the purification effect is not ideal, and it is difficult to completely remove impurity ions

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Crush the gypsum tailings, sieve through a 120-mesh sieve, add 15.00g of crushed gypsum and 300ml of 1.50mol / L hydrochloric acid solution prepared in advance to a 500mL beaker at the same time, and immerse the solution in the above beaker at a constant temperature of 80°C In a water bath, keep the temperature and stir for 5 hours. After the reaction is completed, filter while hot and remove the solid residue not dissolved in the hydrochloric acid solution. The filtrate is transferred to a 500mL beaker, and placed at room temperature for cooling and crystallization for 12 hours. After the crystallization is completed, filter with suction, wash the filter cake with acid, then wash it with water, and then dry the filter cake in an oven at 50°C for 6 hours to obtain 6.89g of high-purity gypsum product with a purity of 98.54%.

Embodiment 2

[0026] Crush the low-grade gypsum ore, sieve it through a 120-mesh sieve, add 30.12g of the crushed gypsum and 600mL of 0.5mol / L nitric acid solution prepared in advance to a 1000mL beaker at the same time, and immerse the solution in the above beaker at 50°C In a constant temperature water bath, keep the temperature constant and stir for 10 hours. After the reaction is completed, suction filter while it is hot, and remove the solid residue not dissolved in the nitric acid solution. After the crystallization is completed, filter with suction, wash the filter cake with acid, then wash it with water, and then dry the filter cake in an oven at 40°C for 12 hours to obtain 14.28g of high-purity gypsum product with a purity of 99.50%.

Embodiment 3

[0028] Crush the gypsum tailings, sieve through a 120-mesh sieve, add 60.00 g of the crushed gypsum and 900 mL of a 1.0 mol / L mixed solution of hydrochloric acid and nitric acid to a 1000 mL beaker at the same time, and immerse the solution in the above beaker in In a constant temperature water bath at 60°C, keep the temperature constant and stir for 2 hours. After the reaction is completed, suction filter while it is hot, and remove the solid residues that are not dissolved in the hydrochloric acid and nitric acid solutions. 18h. After the crystallization is completed, filter with suction, wash the filter cake with acid, then wash it with water, and then dry the filter cake in an oven at 60°C for 2 hours to obtain 35.19 g of high-purity gypsum product with a purity of 98.70%.

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Abstract

The invention relates to the field of preparation of high purity gypsum and particularly relates to a method for purifying low-grade natural gypsum or gypsum tailings by recrystallization. The method provided by the invention mainly comprises the following six steps: crushing; screening; dissolving; crystallizing; washing; and drying. The method specifically comprises the following steps: crushing and screening the low-grade natural gypsum or gypsum tailings; then, adding the low-grade natural gypsum or gypsum tailings into an acid at special solubility; heating to a certain temperature till the low-grade natural gypsum or gypsum tailings is / are fully dissolved; carrying out solid-liquid separation to remove undissolved solid phase impurities while the solution is hot; cooling, recrystallizing a liquid phase at a relatively low temperature and carrying out solid-liquid separation; and washing and drying a filter cake to obtain the high purity gypsum. The liquid phase in the dissolving and crystallizing processes can be repeatedly used. According to the method provided by the invention, proper raw material granularity, solid liquid ratio, temperature and acid concentration are selected and the raw materials are dissolved and crystallized for a certain time to prepare gypsum with relatively high purity, so that the grade or performance of the gypsum is remarkably improved.

Description

technical field [0001] The invention relates to the field of high-purity gypsum preparation, in particular to a method for recrystallizing and purifying low-grade natural gypsum or gypsum tailings. Background technique [0002] Natural gypsum is one of the advantageous minerals in China. The proven reserves are 100 billion tons, ranking first in the world. With the rapid development of my country's construction industry and building materials industry, the demand for gypsum is increasing. The purity requirements are also getting higher and higher. At the same time, high-grade gypsum resources are gradually decreasing, so the full development and utilization of low-grade gypsum or gypsum tailings resources has been paid more and more attention. However, the low-grade natural gypsum or gypsum tailings have complex impurity components, poor gradation, and low purity, which creates obstacles for the resource utilization of low-grade natural gypsum or gypsum tailings. If the gyp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F11/46
Inventor 王敏王怀有赵强赵有璟李锦丽
Owner QINGHAI INST OF SALT LAKES OF CHINESE ACAD OF SCI
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