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Method of utilizing chromium-series regenerated liquid to prepare sodium dichromate

A technology of sodium dichromate and regeneration solution, which is applied in the direction of chromate/dichromate, etc., can solve the problems of complex water quality and difficult control, and achieve the effects of short production cycle, reduced industrial production cost, and reduced pollution

Active Publication Date: 2017-10-20
中新联科环境科技(安徽)有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The wastewater discharged during the production process contains heavy metal ions such as chromium, copper, nickel, highly toxic substances such as cyanide, and a large number of organic pollutants. The water quality is complicated and difficult to control, and it is one of the most difficult industrial wastewater to treat.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Take 2L of chromium-based regeneration solution, filter and remove impurities, slowly add 98% concentrated sulfuric acid to the chromium-based regeneration solution after filtration and remove impurities, adjust its pH to 2, then heat and evaporate the liquid after pH adjustment, and control the temperature at 90°C, when a small amount of solid appears at the bottom of the liquid, stop heating, let stand and cool down to 80°C; then suction-filter the obtained solid-liquid mixture, and keep the filtrate I for later use;

[0020] Next, the filtrate I was placed in an ice-water bath for cold crystallization, the crystallization temperature was controlled at 12°C, and the mixed solution was stirred with a stirrer (the speed was controlled at 120r / min). Rinse the solid, and keep the filtrate II for later use; then continue to place the filtrate II in an ice-water bath for cooling and crystallization, control the crystallization temperature at -8°C, and use a stirrer to stir t...

Embodiment 2

[0023] Take 2L of the chromium-based regeneration solution, filter and remove impurities, slowly add 98% concentrated sulfuric acid to the filtered and removed chromium-based regeneration solution, adjust its pH to 2.2, and then heat and evaporate the pH-adjusted liquid, and control the temperature at 95°C, when a small amount of solid appears at the bottom of the liquid, stop heating, let stand and cool down to 82°C; then suction-filter the obtained solid-liquid mixture, and keep the filtrate I for later use;

[0024] Next, the filtrate I was placed in an ice-water bath for cold crystallization, the crystallization temperature was controlled at 10°C, and the mixed solution was stirred with a stirrer (the speed was controlled at 120r / min). Rinse the solid with water, and keep the filtrate II for later use; then continue to place the filtrate II in an ice water bath for cooling and crystallization. After h, separate by filtration, wash the solid with a small amount of deionized...

Embodiment 3

[0027] Take 2L of chromium-based regeneration solution, filter and remove impurities, slowly add 98% concentrated sulfuric acid to the chromium-based regeneration solution after filtration and remove impurities, adjust its pH to 3, then heat and evaporate the liquid after pH adjustment, and control the temperature at 105°C, when a small amount of solid appears at the bottom of the liquid, stop heating, let stand and cool down to 84°C; then filter the obtained solid-liquid mixture with suction, and keep the filtrate I for later use;

[0028] Next, the filtrate I was placed in an ice-water bath for cold crystallization, the crystallization temperature was controlled at 18°C, and the mixed solution was stirred with a stirrer (the speed was controlled at 120r / min). Rinse the solid and keep the filtrate II for later use; then continue to place the filtrate II in an ice-water bath for cooling and crystallization, the crystallization temperature is controlled at -10°C, and the mixed s...

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PUM

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Abstract

The invention discloses a method of utilizing chromium-series regenerated liquid to prepare sodium dichromate. By the method, environment pollution caused by chromium-series wastewater can be reduced. The method includes following steps: taking the chromium-series regenerated liquid, and filtering to remove impurities; adding 98% concentrated sulfuric acid to adjust PH to reach requirements, heating for evaporation, controlling temperature, stopping heating, standing for cooling, subjecting an obtained solid-liquid mixture to suction filtration, and reserving filtrate for standby use; putting the filtrate into an ice water bath pot for cooling and crystallizing, controlling crystallizing temperature, stirring mixed liquid, filtering and separating, continuing to put filtrate after separation into the ice water bath pot for cooling and crystallizing for 5-6h, filtering and separating, and reserving filtrate for standby use; reheating the filtrate for evaporation, controlling temperature, and stopping evaporation when volume of the filtrate is evaporated to 3 / 5 of original volume; continuing to put liquid into the ice water bath pot for cooling and crystallizing, filtering and separating after cooling and crystallizing, taking filtrate for drying so as to obtain sodium dichromate after drying. By the method, chromium-series regenerated liquid resources are utilized fully and effectively, and environment pollution is reduced.

Description

technical field [0001] The invention relates to the technical field of preparing sodium dichromate, in particular to a method for preparing sodium dichromate by utilizing a chromium-based regeneration solution. Background technique [0002] The electroplating industry is known as one of the three major polluting industries in the world today. The wastewater discharged during the production process contains heavy metal ions such as chromium, copper, nickel, highly toxic substances such as cyanide, and a large number of organic pollutants. The water quality is complex and difficult to control, and it is one of the most difficult industrial wastewater to treat. The waste gas, waste water and waste residue brought by electroplating have caused serious pollution to the environment. Cr is a typical heavy metal pollutant in electroplating wastewater. The main forms of Cr in the water environment are trivalent chromium and hexavalent chromium. Cr(Ⅲ) is an essential trace element fo...

Claims

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Application Information

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IPC IPC(8): C01G37/14
CPCC01G37/14
Inventor 吴文明高洪刚马亮陈圩刘兵李海洋王旭平唐润丰
Owner 中新联科环境科技(安徽)有限公司