CN108315509B - Method for preparing chrome tanning agent by using sodium hydrosulfite - Google Patents
Method for preparing chrome tanning agent by using sodium hydrosulfite Download PDFInfo
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- CN108315509B CN108315509B CN201810064725.5A CN201810064725A CN108315509B CN 108315509 B CN108315509 B CN 108315509B CN 201810064725 A CN201810064725 A CN 201810064725A CN 108315509 B CN108315509 B CN 108315509B
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- tanning agent
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- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
- C14C3/00—Tanning; Compositions for tanning
- C14C3/02—Chemical tanning
- C14C3/04—Mineral tanning
- C14C3/06—Mineral tanning using chromium compounds
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Abstract
The invention belongs to the technical field of environmental protection, and particularly relates to a method for preparing a chrome tanning agent by using sodium hydrosulfite. The method comprises the following effective steps: firstly, removing water-soluble impurities in the chromium-enriched sludge by using water, and filtering; then adding concentrated sulfuric acid into the chromium-rich sludge to dissolve the chromium-rich sludge; then filtering out impurities which are insoluble in acid to obtain chromium-containing filtrate; adding sodium bichromate and concentrated sulfuric acid into the chromium-containing filtrate, heating, adding glucose, and continuing to react; after reacting for 2-3 hours, adding sodium hydrosulfite into the feed liquid to continue reacting until hexavalent chromium in the feed liquid completely disappears; and adjusting the alkalinity of the chromium-containing filtrate to be between 32 and 34 percent, and performing spray drying after filter pressing to obtain the chrome tanning agent. The invention solves the technical problem of chromium-containing sludge pollution by a scientific preparation method, and simultaneously ensures that the tanning effect of the prepared chrome tanning agent reaches the same products of brothers, turkeys and other brands, the shrinkage temperature is equivalent, the fullness is equivalent, and the color is lighter.
Description
Technical Field
The invention belongs to the technical field of environmental protection, relates to the recycling of chromium-rich sludge, and particularly relates to a method for preparing a chrome tanning agent by using sodium hydrosulfite.
Background
Tanning refers to the process of tanning hides into leather. Removing hair and non-collagen fiber, loosening, fixing and strengthening collagen fiber in dermis, and treating with a series of chemical (including biochemical) and mechanical treatments. The tanning process is generally divided into three stages of preparation, tanning and finishing. The most used equipment in the leather making process is a rotary drum, the procedures of soaking, liming, unhairing, softening, pickling, tanning, dyeing, emulsion oiling and the like are all finished in the rotary drum, and the uniform penetration of various chemical materials is promoted through the mechanical action of the rotary drum to finish the chemical action of the preparation on leather.
A large amount of chromium-containing wastewater is generated in the tanning process, chromium-rich sludge is directly derived from chromium cakes generated by treating chrome tanning wastewater, and a large amount of chromium hydroxide and a small amount of trivalent chromium compounds in other forms are accumulated in the part of solid waste.
At present, the main treatment methods at home and abroad are as follows: landfill, incineration and self recycling of enterprises. The landfill and the burning method can not eliminate and reduce the pollution of the chromium-rich sludge chromium and have the hidden danger of secondary pollution. Due to the limitation of enterprises, the reuse effect is poor due to simple impurity removal and acidification, so that the quality of the leather is seriously reduced. And a large amount of the waste water is illegally dumped and buried by enterprises, so that the environment is greatly polluted. If the chromium-free chromium-.
In order to achieve the purposes of saving energy and recycling, people propose various treatment methods according to the physicochemical characteristics of the chromium-rich sludge, but the existing method for treating the chromium-rich sludge to produce the chrome tanning agent has extremely poor effect, causes the color of leather to be very dark green or dark yellow, and has the chromium absorption rate lower than that of normal chromium powder by 10-20%; and the content of the powdery chrome tanning agent prepared by directly using the chromium-containing sludge hardly reaches the standard of 25 percent.
Disclosure of Invention
Aiming at the technical problems existing in the prior process of preparing the chrome tanning agent by treating the chromium-rich sludge, the invention provides the method for preparing the chrome tanning agent by utilizing the sodium hydrosulfite, which has the advantages of reasonable design, simple method, low cost and suitability for industrial production.
In order to achieve the purpose, the invention adopts the technical scheme that the invention provides a method for preparing a chrome tanning agent by using sodium hydrosulfite, which is characterized by comprising the following effective steps:
a. firstly, removing water-soluble impurities in the chromium-enriched sludge by using water, and filtering;
b. then adding concentrated sulfuric acid into the chromium-rich sludge to dissolve the chromium-rich sludge;
c. then filtering out impurities which are insoluble in acid to obtain chromium-containing filtrate;
d. adding sodium bichromate and concentrated sulfuric acid into the chromium-containing filtrate, heating, adding glucose, and continuing to react;
e. after reacting for 2-3 hours, adding sodium hydrosulfite into the feed liquid to continue reacting until hexavalent chromium in the feed liquid completely disappears;
f. and adjusting the alkalinity of the chromium-containing filtrate to be between 32 and 34 percent, and performing spray drying after filter pressing to obtain the chrome tanning agent.
Preferably, in the step a, the water consumption is twice of the mass of the chromium-rich sludge, and the water temperature is controlled to be 50 ℃.
Preferably, in the step d, the temperature is raised to 90 to 100 ℃.
Preferably, in the step d, the addition amount of the sodium bichromate is equal to the chromium content of the chromium-containing filtrate.
Preferably, in the step d, the adding amount of the glucose is 8-18% of the amount of the sodium bichromate, and the amount of the concentrated sulfuric acid is 0.9-1.2 times of the weight of the sodium bichromate.
Preferably, in the step e, the adding amount of the sodium hydrosulfite is 3.5-12% of the amount of the sodium bichromate.
Compared with the prior art, the invention has the advantages and positive effects that,
1. the invention provides a method for preparing chrome tanning agent by using sodium hydrosulfite, which solves the technical problem of chromium-containing sludge pollution by a scientific preparation method, and simultaneously leads the prepared standard chrome tanning agent with 25 +/-1 percent of chromium content (Cr2O3) and 33 +/-1 percent of alkalinity to achieve the tanning effect of similar products of brothers, Turkey and other brands, and has the advantages of equivalent shrinkage temperature, equivalent fullness and lighter color.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, the present invention will be further described with reference to the following examples. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and thus the present invention is not limited to the specific embodiments of the present disclosure.
Example 1 this example provides a process for the preparation of a chrome tanning agent using sodium dithionite
The embodiment aims to provide a method for removing water-soluble impurities in the chromium-rich sludge by using water and filtering, wherein in the step, the water consumption is twice of the mass of the chromium-rich sludge, the water temperature is controlled at 50 ℃, and the main purpose of removing soluble salts in the chromium-rich sludge is to do so. The main purpose of filtration is to remove the water, and thus most of the soluble salts.
Then, adding concentrated sulfuric acid into the chromium-rich sludge, adjusting the pH value to be about 2-3, dissolving the chromium-rich sludge, filtering again, and removing impurities insoluble in acid to obtain the chromium content (in terms of Cr)2O3In this embodiment, the addition amount of the sodium bichromate is based on the equivalent of the chromium content of the sodium bichromate and the chromium content of the chromium-containing filtrate, and the addition amount of the concentrated sulfuric acid is 0.9 times of the weight of the sodium bichromate.
Then, the chromium-containing filtrate is heated to 90-100 ℃, glucose is added, the main function of the glucose is to reduce hexavalent chromium, the addition amount of the glucose is also added according to the amount of sodium bichromate, and in the embodiment, the addition amount of the glucose is 8% of the amount of the sodium bichromate.
After reacting for 2-3 hours, most hexavalent chromium is reduced into trivalent chromium, the feed liquid is a crude liquid chrome tanning agent, in order to improve the performance of the finished chrome tanning agent, then adding sodium hydrosulfite to continue reaction until hexavalent chromium in the chromium-containing filtrate completely disappears, obtaining the finished liquid chrome tanning agent, wherein the sodium hydrosulfite has two functions, one is used for reducing the hexavalent chromium, the other is used for improving the performance of the chrome tanning agent, and researches show that the addition of the sodium hydrosulfite can improve the performance of the finished chrome tanning agent to ensure that the finished chrome tanning agent completely meets the requirements, and can ensure that the shrinkage temperature and the fullness of the leather after chrome tanning are equivalent to those of the commercial standard chrome tanning agent, and the color is lighter, meanwhile, the addition amount of sodium hydrosulfite is also based on the addition amount of sodium bichromate, and specifically, the addition amount of sodium hydrosulfite is 12 percent of the weight of the sodium bichromate.
In order to improve the performance and standard of the chrome tanning agent, the alkalinity of the liquid chrome tanning agent needs to be adjusted, so that the alkalinity of the chrome-containing filtrate is adjusted to be between 32% and 34%, the alkalinity can be adjusted by using an alkali plate or sulfuric acid, and of course, other raw materials can be used for adjustment, which is the prior common technology, and in the embodiment, the alkali plate or the sulfuric acid is preferably considered.
And after the alkalinity is adjusted, carrying out filter pressing and spray drying to obtain the chrome tanning agent. Detecting, spray drying to obtain chromium content (Cr)2O3)25 plus or minus 1 percent and alkalinity of 33 plus or minus 1 percentThe standard type chrome tanning agent has the tanning effect reaching similar products of brothers, Turkey brands and the like, and has the advantages of equivalent shrinkage temperature, equivalent fullness and lighter color.
Example 2 this example provides a process for the preparation of chrome tanning agent using sodium dithionite
The embodiment aims to provide a method for removing water-soluble impurities in the chromium-rich sludge by using water, and water-soluble substances in the chromium-rich sludge are removed by using water and filtered, wherein in the step, the water consumption is twice of the mass of the chromium-rich sludge, the water temperature is controlled at 50 ℃, and the main purpose of removing soluble salts in the chromium-rich sludge is realized. The main purpose of filtration is to remove the water, and thus most of the soluble salts.
Then, adding concentrated sulfuric acid into the chromium-rich sludge, adjusting the pH value to be about 2-3, dissolving the chromium-rich sludge, filtering again, and removing impurities insoluble in acid to obtain the chromium content (in terms of Cr)2O3In this embodiment, the addition amount of the sodium bichromate is based on the equivalent of the chromium content of the sodium bichromate and the chromium content of the chromium-containing filtrate, and the addition amount of the concentrated sulfuric acid is 1.2 times of the weight of the sodium bichromate.
Then, the chromium-containing filtrate is heated to 90-100 ℃, glucose is added, the main function of the glucose is to reduce hexavalent chromium, the addition amount of the glucose is also added according to the amount of sodium bichromate, and in the embodiment, the addition amount of the glucose is 18% of the amount of the sodium bichromate.
After reacting for 2-3 hours, most hexavalent chromium is reduced into trivalent chromium, the feed liquid is a crude liquid chrome tanning agent, in order to improve the performance of the finished chrome tanning agent, then adding sodium hydrosulfite to continue reaction until hexavalent chromium in the chromium-containing filtrate completely disappears, obtaining the finished liquid chrome tanning agent, wherein the sodium hydrosulfite has two functions, one is used for reducing the hexavalent chromium, the other is used for improving the performance of the chrome tanning agent, and researches show that the addition of the sodium hydrosulfite can improve the performance of the finished chrome tanning agent to ensure that the finished chrome tanning agent completely meets the requirements, and can ensure that the shrinkage temperature and the fullness of the leather after chrome tanning are equivalent to those of the commercial standard chrome tanning agent, and the color is lighter, meanwhile, the addition amount of sodium hydrosulfite is also based on the addition amount of sodium bichromate, and specifically, the addition amount of sodium hydrosulfite is 3.5 percent of the weight of the sodium bichromate.
In order to improve the performance and standard of the chrome tanning agent, the alkalinity of the liquid chrome tanning agent needs to be adjusted, so that the alkalinity of the chrome-containing filtrate is adjusted to be between 32% and 34%, the alkalinity can be adjusted by using an alkali plate or sulfuric acid, and of course, other raw materials can be used for adjustment, which is the prior common technology, and in the embodiment, the alkali plate or the sulfuric acid is preferably considered.
And after the alkalinity is adjusted, carrying out filter pressing and spray drying to obtain the chrome tanning agent. Detecting, spray drying to obtain chromium content (Cr)2O3)25 +/-1 percent of standard type chrome tanning agent with alkalinity of 33 +/-1 percent, achieves the tanning effect of similar products of brothers, turkeys and other brands, has equivalent shrinkage temperature and fullness, and is lighter in color.
Example 3 this example provides a process for preparing a chrome tanning agent using sodium dithionite
The embodiment aims to provide a method for removing water-soluble impurities in the chromium-rich sludge by using water, and water-soluble substances in the chromium-rich sludge are removed by using water and filtered, wherein in the step, the water consumption is twice of the mass of the chromium-rich sludge, the water temperature is controlled at 50 ℃, and the main purpose of removing soluble salts in the chromium-rich sludge is realized. The main purpose of filtration is to remove the water, and thus most of the soluble salts.
Then, adding concentrated sulfuric acid into the chromium-rich sludge, adjusting the pH value to be about 2-3, dissolving the chromium-rich sludge, filtering again, and removing impurities insoluble in acid to obtain the chromium content (in terms of Cr)2O3Calculated) 7 to 9 percent of chromium-containing filtrate, then adding sodium bichromate and concentrated sulfuric acid into the chromium-containing filtrate, wherein the main functions of adding the sodium bichromate are to improve the chromium content and remove part of organic matters in chromium mud by utilizing the strong oxidizing property of the sodium bichromate, thereby ensuring the preparationThe chrome tanning agent prepared meets the standard, in the embodiment, the addition amount of sodium bichromate is based on the condition that the chromium content is equal to the chromium content in the chromium-containing filtrate, and the addition amount of concentrated sulfuric acid is 1.1 times of the weight of the sodium bichromate.
Then, the chromium-containing filtrate is heated to 90-100 ℃, glucose is added, the main function of the glucose is to reduce hexavalent chromium, the addition amount of the glucose is also added according to the amount of sodium bichromate, and in the embodiment, the addition amount of the glucose is 14% of the amount of the sodium bichromate.
After reacting for 2-3 hours, most hexavalent chromium is reduced into trivalent chromium, the feed liquid is a crude liquid chrome tanning agent, in order to improve the performance of the finished chrome tanning agent, then adding sodium hydrosulfite to continue reaction until hexavalent chromium in the chromium-containing filtrate completely disappears, obtaining the finished liquid chrome tanning agent, wherein the sodium hydrosulfite has two functions, one is used for reducing the hexavalent chromium, the other is used for improving the performance of the chrome tanning agent, and researches show that the addition of the sodium hydrosulfite can improve the performance of the finished chrome tanning agent to ensure that the finished chrome tanning agent completely meets the requirements, and can ensure that the shrinkage temperature and the fullness of the leather after chrome tanning are equivalent to those of the commercial standard chrome tanning agent, and the color is lighter, meanwhile, the addition amount of sodium hydrosulfite is also based on the addition amount of sodium bichromate, and specifically, the addition amount of sodium hydrosulfite is 9 percent of the weight of the sodium bichromate.
In order to improve the performance and standard of the chrome tanning agent, the alkalinity of the liquid chrome tanning agent needs to be adjusted, so that the alkalinity of the chrome-containing filtrate is adjusted to be between 32% and 34%, the alkalinity can be adjusted by using an alkali plate or sulfuric acid, and of course, other raw materials can be used for adjustment, which is the prior common technology, and in the embodiment, the alkali plate or the sulfuric acid is preferably considered.
And after the alkalinity is adjusted, carrying out filter pressing and spray drying to obtain the chrome tanning agent. Detecting, spray drying to obtain chromium content (Cr)2O3)25 +/-1 percent of standard type chrome tanning agent with alkalinity of 33 +/-1 percent, achieves the tanning effect of similar products of brothers, turkeys and other brands, has equivalent shrinkage temperature and fullness, and is lighter in color.
By detecting the chrome tanning agents produced in the embodiments 1, 2 and 3, all indexes of the chrome tanning agents completely meet the standard of GBT 24331-2009 on the powdery chrome tanning agent for tanning, and the technical problem in the prior art is further solved.
The above description is only a preferred embodiment of the present invention, and not intended to limit the present invention in other forms, and any person skilled in the art may apply the above modifications or changes to the equivalent embodiments with equivalent changes, without departing from the technical spirit of the present invention, and any simple modification, equivalent change and change made to the above embodiments according to the technical spirit of the present invention still belong to the protection scope of the technical spirit of the present invention.
Claims (1)
1. A method for preparing chrome tanning agent by using sodium hydrosulfite is characterized by comprising the following effective steps:
a. firstly, removing water-soluble impurities in the chromium-enriched sludge by using water, and filtering;
b. then adding concentrated sulfuric acid into the chromium-rich sludge to dissolve the chromium-rich sludge;
c. then filtering out impurities which are insoluble in acid to obtain chromium-containing filtrate;
d. adding sodium bichromate and concentrated sulfuric acid into the chromium-containing filtrate, heating, adding glucose, and continuing to react;
e. after reacting for 2-3 hours, adding sodium hydrosulfite into the feed liquid to continue reacting until hexavalent chromium in the feed liquid completely disappears;
f. adjusting the alkalinity of the chromium-containing filtrate to 32-34%, and performing spray drying after filter pressing to obtain a chromium tanning agent;
in the step a, the water consumption is twice of the mass of the chromium-rich sludge, the water temperature is controlled to be 50 ℃, in the step d, the temperature is raised to 90-100 ℃, in the step d, the addition amount of glucose is 8-18% of the amount of sodium bichromate, the amount of concentrated sulfuric acid is 0.9-1.2 times of the weight of the sodium bichromate, and in the step e, the addition amount of sodium hydrosulfite is 3-12% of the amount of the sodium bichromate.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102363820A (en) * | 2011-09-22 | 2012-02-29 | 兄弟科技股份有限公司 | Reutilization method of chromium-containing leather production sludge |
| CN103014191A (en) * | 2012-12-13 | 2013-04-03 | 四川大学 | Method for recovering collagen and chromium salts from chromium-containing scrap leather residues |
| CN104263861A (en) * | 2014-10-10 | 2015-01-07 | 中国科学院城市环境研究所 | Method for preparing chrome tanning agent from chromium-containing wastewater concentrate in electroplating centralized control area |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102363820A (en) * | 2011-09-22 | 2012-02-29 | 兄弟科技股份有限公司 | Reutilization method of chromium-containing leather production sludge |
| CN103014191A (en) * | 2012-12-13 | 2013-04-03 | 四川大学 | Method for recovering collagen and chromium salts from chromium-containing scrap leather residues |
| CN104263861A (en) * | 2014-10-10 | 2015-01-07 | 中国科学院城市环境研究所 | Method for preparing chrome tanning agent from chromium-containing wastewater concentrate in electroplating centralized control area |
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