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the water influence the the emulsion liquid in aluminum hot rolling

 The roling type of Aluminum sheet and aluminumstrip  includes hot rolling of aluminum sheet with heavy plate and aluminum coil in production and cold rolling of aluminum sheet and foil rolling. The aluminum rolling process lubricants are mainly made of emulsion, cold rolled aluminum plate, rolled oil, aluminum foil used for rolling oil, cold rolled aluminum plate and water application. Aluminium hot rolling with emulsion composed of hot rolling oil and water mix, the concentration of the emulsion is usually in the range of 2-10%, including aqueous emulsion of about 90 ~ 98%, therefore, the water in the aluminium hot rolling emulsion for aluminium hot rolling production and the strip quality, play a very important role. This paper will briefly discuss the water and related factors of aluminum hot rolling emulsion.

1. Natural water distribution,
Calcium and magnesium ions in natural water are the most harmful to emulsion. Calcium and magnesium ions can be contrasted with emulsifiers in emulsion and some effective components and to the stability of the emulsion and the effect of active ingredients play a big impact, not only affect the stability of the emulsion is used, they may affect the normal conduct of rolling process at the same time.
In addition to calcium and magnesium ions, other ions in the water will also have adverse effects on the emulsion, such as high content of Na +, which can increase the corrosion tendency of water and reduce the chemical adsorption of active components in the emulsion. Emulsions with high hardness of water, including sulfates or oxides, can reduce the stability of emulsion. Here are the possible effects of several major ions.
The main effects of ions on water quality in water:
1. Ca2 +, Mg2+ (calcium and magnesium ions) : reacts with alkaline substances to form insoluble substances, such as the insoluble scale in the exchangers; Can react with related active ingredients in emulsion.
2. Cl- (chloride ion) : corrosive ion, corrosion of metal; Increase salt in water.
3. SO42- (sulfate ion) : increase the salt content of water; Ca2+ combined with calcium sulfate scale.
4. HCO3- : (hydrogen carbonate) : decomposition can produce alkaline corrosion; The steam produces CO2 corrosion.
5. Na+ (sodium ion) : increase the salt content of water; Increase the corrosion tendency of water.
2. Softening water distribution,
Due to large the dangers of calcium and magnesium ions, for this reason, people USES sodium ion exchange resin, sodium at a price to replace the divalent calcium, magnesium, so from a certain extent, reduce the calcium, the dangers of magnesium ions. The hardness of the water is much lower after using sodium instead of calcium and magnesium. However, the content of metal ions in the emulsion has not decreased, so the conductivity does not change significantly.
If adopted by the natural water with high hardness, so in the preparation of sodium ion exchange water will have a lot of Na + ions and a certain content of Cl - ions into the emulsion, become the main ions in emulsion. When the content of Na+ ions and Cl- ions in emulsion is low, their use of emulsion and the influence of production are often small. But as the rolling process progresses, the water of the emulsion evaporates, the ions in the emulsion will not evaporate, and these ions accumulate, and their damage starts to increase. As the content of sodium ions in the water increases, the conductivity increases, the corrosion speed is accelerated, because the water resistance decreases, the corrosion current is easy to pass, thus the electrochemical effect is accelerated. In addition, small sodium ion radius, strong penetrating power, strong polarity, with concentration of its content, a lot of sodium ions will be damaged to some extent effective component molecules in the chemical adsorption on the roll, the lubrication effect of emulsion is affected, and a lot of sodium ions formed by sodium soap will deteriorate the emulsion separability, influence the lubricity, along with the bubble at the same time, further worsening lubricity, so when the Na + ion content is too high, viscose aluminum surface defects may occur, in addition, the sodium content is too high, may also increase the emulsion usage.
This kind of situation, appeared at a customer, due to the use of demineralized water (sodium ion exchange water) of high conductivity, accumulate a large amount of sodium ions quickly, when the electrical conductivity of emulsion reached 1500 us/cm, the surface of the rolling quality problems began. After the user replaced the ionized water, their production and the use of the emulsion were significantly improved.
As mentioned above, the presence of chloride ion can easily cause some corrosion to the metal, and also accelerate the corrosion reaction.
3. Use deionized water distribution
As for aluminum hot rolling emulsion water distribution, deionized water is the best choice. The use of deionized water to remove the water from the water can fundamentally eliminate the effects of water quality on the emulsion, and the potential damage of ions in water will no longer exist. The direct hazards of Ca2 +, Mg2 +, and Na +, Cl- plasma accumulation will be minimized. So, in daily use emulsion, the metallic ions in plate rolling into the emulsion, can through the daily maintenance to eliminate or reduce, so, emulsion can better, long-term for the stability of the rolling and obtain a good surface quality and service.

The requirements of the water and liquid water for aluminum hot rolling emulsion were required
1. General test items and index requirements for liquid water distribution:
Project test results
Hardness (PPM) 0
Electrical conductivity (uS/cm) <10~20
PH 6 to 7
Chloride ion content (PPM) 0
In addition to the requirements for the water distribution of the liquid, it is necessary to make certain requirements on the temperature and the solution of the liquid.
2. Liquid water temperature
Liquid water temperature is greater than 40 degrees, the water's surface tension is very large (73), non-wetting oil on the interface, it is hard to oil emulsion into the water, and hot water surface tension is relatively small, can be smaller oil viscosity, thermal motion is conducive to molecular motion and dispersion, in addition, the rational use of emulsifiers, as well as the cycle of necessary mechanical shear force, can let the oil well dispersed into the water phase, forming good oil-in-water emulsion, and get good use in aluminium hot rolling production.
3. Liquid distribution
In terms of aluminium hot rolling, the emulsion used in the steady state, the granularity distribution and the stability of the emulsion has the strict request, therefore, the liquor when refueling, circulation system and so on also have certain requirements.
Preparation aluminium hot rolling emulsion, the rolling oil must be added to water preparation, if the rolling oil emulsification is very good, can be directly to the emulsion added to water, stirring, can quickly emulsion formed state of emulsion. But most of the rolling oil is prepared, it is necessary to add liquid in the circulating pump, and with the mechanical shearing force of the circulating pump, the distribution of oil bead can be formed reasonably, and it is suitable for the oil-type emulsion of hot rolled production.
Four, conclusion
Aluminum hot rolling has a large proportion of water in emulsion, and the choice of liquid water is of vital importance to the stability of emulsion and the production and quality of the belt. As for aluminum hot rolling emulsion water distribution, deionized water is the best choice. The selection of liquid water index detection and control and liquid water temperature and distribution method is very beneficial to good production and aluminum plate quality.

Henan Changyuan Aluminum Industry Co., Ltd


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