Method for preparing chrome tanning agent from leather-making chromium-containing waste

Abstract

The invention provides a method for preparing a chrome tanning agent from leather-making chromium-containing waste. The method comprises the following steps of: pre-treating leather-making chromium-containing scrap leather slag or chromium mud to obtain chromium mud with protein content of 1%-3% and moisture content of 80%-95%; taking 100 parts by mass of the pre-treated chromium mud to mix with 5-20 parts by mass of concentrated sulfuric acid, stirring at a temperature not lower than 30 DEG C to perform hydrolysis reaction for 15-30 minutes; cooling to the room temperature after reaction timereaches, and performing solid-liquid separation to obtain filtrate; and concentrating the filtrate until solid content is 45-65%, thereby obtaining the chrome tanning agent. According to the method provided by the invention, hydrolysis degree of collagen in chromium mud is controlled, and a utilization rate of Cr2O3 in leather-making waste is improved; the prepared chrome tanning agent is good intanning property, can be independently used; and quality of made leather can reach standard requirements.

Description

technical field [0001] The invention belongs to the field of recycling and utilization of chrome-containing waste materials in tanning, and relates to a method for preparing a chrome tanning agent by using chrome-containing waste materials in tanning, especially for utilizing chrome-containing waste skin dregs and producing remaining chrome sludge waste materials by using chromium-containing waste skin dregs A method of preparing a chrome tanning agent is carried out. Background technique [0002] Chromium-containing waste hide slag is the waste chromium scrap scraped off from chrome-tanned wet leather during the process of tanning, splitting, and trimming. According to statistics, my country's tanning industry can produce about 1.4 million tons of chrome every year. Chromium-containing waste skin residue. More than 90% of this waste is collagen and contains 2-4% Cr 2 o 3 . Among them, collagen is an important protein resource, and chromium is also a kind of valuable heav...

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Problems solved by technology

[0005] Using protein in chrome mud instead of sugar to prepare chrome tanning agent can remove and hydrolyze collagen. When the amount of organic matter in chrome mud is 1:1:1.3 with the amount of added sulfuric acid and red vitriol, a main tanning agent with good performance can be obtained. (Wang Kunyu et al. Preparation of chromium-containing main tanning agent with chrome mud and its performance research [J]. China Leather, 2002 (10): 13-15.), but the chrome tanning agent prepared by this technology is mainly through the additional addition of Red alum exerts the tanning effect, and the chrome contained in the chrome mud has poor tanning performance. When it is reused as a chrome tanning agent, it can no longer combine with the protein on the skin collagen to exert the tanning performance, and the purpose of recycling chromium resources has not been fully achieved.

[0006] Melt the chromium cake with sulfuric acid, then add alkali to dissolve the Cr 2 o 3 Precipitate out, and the obtained precipitate can also be obtained after dissolving with sulfuric acid again (Pan Zhijuan, Wang Kunyu, etc. Recycling technology of chrome leather shavings [J]. Leather Science and Engineering, 2001 (09): 7-11 .) This method needs to add more concentrated sulfuric acid, so not only the salt content of the recovered chrome tanning agent is greatly increased in the process of repeatedly adding acid and alkali, but also the obtained chrome tanning agent needs to be mixed with conventional chrome tanning agents for Leather tanning, the method is too complex and recycles Cr 2 o 3 The utilization rate is not high

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