Leather making is pollution a serious professional, tanning waste water is mainly composed of protein, fat and other organic matter and chromium, sulfide, dyestuff, surface active agent, etc. The characteristics of these contaminants is alkaline, high oxygen consumption, suspended solids And has the toxic substances such as chromium. A serious impact on the problem of pollution ecological environment, has become a professional to carry out the obstacle. At present, we only the future that is, attach importance to the problem of pollution, take the science and technology technique make it gradually complete cleaning production. In the process of producing cut or eliminate pollution, took to the track of sustainable development, deepen has secured the position of the international leather power, for the development of national economy to greater dedication.
Cattle upper leather for shoes as many leather company’s main products, to ensure quality requirements should also think about the implementation of cleaning technology together.
Leather material choose and buy
Cow leather material is mainly salt and frozen skin, dry skin and less bright skin. As far as possible use fresh leather production, is a good way to dispose of salt pollution, but this requires slaughtering and processing and disposal of the distance between can’t do more than a few hours, especially in areas of high temperature and time, this does not practice for most of the tannery. After frozen keep fresh skin can dispose of the above shortcomings, both to dispose of salt pollution, and can be within the range must be shipped, if tannery equipped with cold storage, frozen keep fresh skin can be used as the preferred the original, only the first for freezing treatment can be.
Current home because the original leather from the less developed the vast rural areas, have less slaughter and slaughterhouses do not have reserved frozen equipment, salt wet skin still account for the vast majority, tannery is the main origin of choose and buy the original leather. Tannery in this case the original PiKu if pay attention to the repeated use pickled skin with salt, still can save more than 10% of the salt, the concrete measures are fine salt (coarse salt can damage aside first purchase), with proper preservatives used (e.g., busan1193), as well as ensure that salt is abundant, but also avoid using halophilic bacteria reproduction after repeated damage to the cortex.
Prepare the operating
Leading the preparation section of drum is equipped with multiple drain, make frowsty alternative water wash wash more convenient. In fact frowsty alternative water wash wash not only can save 30% of water consumption, and water to wash effect. Running water to wash the drawback is that the skin together in the process of irrigation and drainage, to reach and cleaning it will extend the washing time, water inside the drum can’t control; Too much difficult to clear water, too little mechanical break is too strong, easy happening in cattle face expel during loose surface, such as abdominal grain serious shortcomings. Manipulation of the washing process throughout the entire produce leather wet process operation.
1. The manipulation of the flooding process
Flooding is the key of the leather production process, the stand or fall of upper flooding and close relationship between the quality of the leather: flooding, as leather empty pine; Flooding the lack of the hair removal liming, uneven fiber divided evenly, into hard and bad parts, leather board fullness. Immersion focus on “moderate” advisable, because domestic raw skin origin, keeping curing is not standard, internship in the manipulation of the “moderate” is never easy. Let’s send now traditional flooding, e.g. to meat – Lord of flooding, in all key elements of liquid ratio, fungicide, ph, temperature and mechanical action are leads people to pay attention to extensively, but domestic degree of raw hide salt rock is larger, the concentration of salt is the most easy to ignore in the soaking process factors. Repeated practice shows that the early stage of the flooding, the concentration of salt stability in 6 wave beauty or above, flooding quality of simple manipulation, as shown in the following flooding technology.
Water is 180%
The temperature of 25 ℃ + 1
Soda ash 0.1% ~ 0.2%
Back to 0.2% wet agent
10 minutes, ph = 8 ~ 8.5, more than 6 wave beauty, 20 minutes, 30 minutes, 20 minutes, 30 points, 10 ~ 15 hours, washed, go to the meat.
The main flooding:
Water is 200%
The temperature of 25 ℃ + 1
Soda ash 0.3%
Back to 0.1% wet agent
After 30 minutes, turn to 10 minutes per hour, a total of 12 ~ 15 hours.
Main flooding after ph = 9 ~ 9.5 advisable, to see if immersed lack can be put together, after the main flooding to abundant water, make sure that doesn’t make the skin excessive salt and affect the beige swell.
2. The hair removal of liming technology thinking again
Enzyme depilation can completely avoid sodium sulphide, cleaning technology is acknowledged as the specification. Choose this kind of technology, in the preparation process of cod value can be cut by 30% ~ 30%, but according to the quality of the leather thinking and processing process is easy to control, the present stage is difficult to promote.
Late small liquid than waxing liming, hydrating swelling is the more sophisticated process, as well as to ensure the quality of leather processing can reduce the dosage of sodium sulphide, progress from liming uniformity, opened the leather grain, reduce the dosage of pollutants of various thinking three improvements for this technology, more ambitious.
(1) adjust early fluid than 0.6 ~ 0.8. General use hair removal than small fluid should be control in the process of hair removal raw hides in no swelling state. Hair removal with water after the completion of the raw skin filling water swelling, lax fiber further, but in the late hair removal, when liquid ratio greater than 0.8, the rawhide beginning swell, saturated robust against barilla, should be adjusted to 0.8 below. Only strict control hair removal liquid than can ensure uniform hair removal in the process of the materials and chemical soaking.
(2) cutting dosage of sulfide material consumptions, because lower liquid ratio, on the premise of ensure the depilation concentration, proper cut sulfide dosage, neither affect hair removal and beige swelling effect, also can reduce pollution emissions, 1% ~ 1.2% sodium hydrosulphide and 0.4% ~ 0.4% sodium sulphide for optimum dosage, can be on the basis of technology usually reduce the use of 10% ~ 20%, but the quality does not affect the function.
Many times (3) choose delay add water, add water to make more tenderness, swelling process make prints more level off, the grey leather cleaner. After points to participate in the sulfur sodium hydride, sodium sulfide and liming agents, in hair removal after the completion of no water immediately (after adding water into the process of filling water swelling, and grey liming liquid alkali concentration and penetration velocity significantly reduced, and even to cut off the swell uneven), but after the grey lye thoroughly soak hides longitudinal section beginning with water.
If water process is also very fastidious, one-time all attend the excessive concentration of lower gradient in the drum, the skin filling water agile appearance, affected the beige uniform swell, middle fiber distractions effect is poor. So in 40% water 2 ~ 3 hours later, after the concentration balance inside the drum skins you list again for the remaining 100% of water as well, so grey skin swelling slow, even, and the grain growth is flat and level.
Hair removal liming:
Water is 60%
23 ~ 25 ℃ temperature
The sulfur sodium hydride 1% ~ 1.2%
Liming agent 0.3%
30 minutes, stop 30 minutes;
Sodium sulfide 0.4% ~ 0.6%