Electroplating sludge is the final state of electroplating wastewater treatment, which contains a large number of precious metals such as copper, nickel, chromium, iron, zinc and so on. Electroplating sludge mainly comes from the solid waste produced by various electroplating waste liquid and electrolyzer liquid after liquid-phase chemical treatment. Due to the different production and treatment processes of electroplating plants, the chemical composition of electroplating sludge is quite complex, mainly containing chromium, iron, nickel, copper, zinc and other heavy metal compounds and soluble salts.
In the initial treatment of electroplating sludge, electroplating enterprises need to convert all kinds of heavy metal salts in electroplating wastewater into corresponding hydroxides and precipitate and solidify them. Therefore, in general, electroplating manufacturers add relevant chemicals such as reducing agent, neutralizing agent and flocculant in the treatment of electroplating wastewater, resulting in the increase of chemical components in electroplating sludge, All kinds of heavy metal compounds are dispersed in the components but the content is low. In particular, some electroplating enterprises use lime or calcium carbide as neutralizing agent to produce a large amount of gypsum or calcium hydroxide through chemical reaction during neutralization treatment, which makes the total amount of electroplating sludge increase and the content of heavy metal components decrease, which makes further harmless treatment, separation and comprehensive utilization more difficult. According to our field investigation, the water content of electroplating sludge produced by new treatment is very high, up to 75% ～ 80%. The compound content of chromium, iron, nickel, copper and zinc is generally about 0.5% ～ 3% (in terms of oxides), gypsum (calcium sulfate) is 8% ～ 10%, and other water-soluble salts and impurities are about 5%.
Special hollow for electroplating sludge paddle dryer
Parameters and requirements provided by customers:
1. Material: Electroplating Sludge
2. Initial moisture: 75%
3. Final moisture: 50%
4. Drying temperature: 250 ℃
5. Heating method: heat transfer oil
6. Material: 16 manganese steel equipment
7. Installation: Indoor
8. Power supply: 380V, 50Hz, three-phase, four wire
9. Environment: 20 ℃ 760mmhg relative humidity: φ = 80%
According to the above parameters provided by customers, our company designed and customized kjg-80 electroplating sludge hollow paddle dryer for Suzhou Huating special electroplating company. After a period of operation, the drying effect is very ideal.
The wedge-shaped hollow blades are densely arranged on the hollow shaft. The hot medium steam flows through the hollow shaft and the heat transfer area per unit effective volume is large. The heat transfer medium flows through the shell jacket and the hollow stirring shaft through the rotary joint. The hollow stirring shaft has different internal structures according to the type of hot medium, so as to ensure the good heat transfer effect. When the blade and jacket are heated by hot medium, the upper part of the outlet is dehumidified at the same time, which greatly increases the drying strength of the equipment. The evaporated water is taken out of the dryer by the dehumidification fan.
1. The energy consumption of paddle dryer is low: due to indirect heating, there is no large amount of air to take away heat, and the outer wall of the dryer is provided with insulation layer, so the heat loss is very small.
2. The cost of the blade dryer system is low: the unit effective volume has a huge heat transfer surface, which shortens the processing time. The size of the equipment is smaller and the floor area is reduced.
3. A wide range of processing materials: using different thermal media, it can handle both heat sensitive materials and materials requiring high temperature treatment.
4. Small environmental pollution: the amount of carrying air is very small, and the dust material is very little.
5. The operation cost is low.
6. Stable operation: due to the special compression expansion mixing effect of wedge blade, the material particles fully contact with the heat transfer area, and the temperature, humidity, mixing temperature and gradient of the material are very small in the axial range, thus ensuring the stability of the process.