Industrial byproduct gypsum  mainly refers to flue gas desulphurization gypsum, phosphorus gypsum, citric acid gypsum and fluorine gypsum, and normally has dihydrate gypsum (CaSO4.2H2O) shape; desulphurization gypsum  and phosphorus gypsum are frequently used. Comparing with natural gypsum, water content in desulphurization gypsum and phosphorus gypsum is high, water content of desulphurization gypsum is normally 12%-18%, but water content of phosphorus gypsum is about 20%-25%. Desulphurization gypsum contains excessive  chlorine compound; phosphorus gypsum, as byproduct of wet process phosphoric acid, often contains residual phosphate, sodium and fluorine compounds. Above features  directly determine producing industrial byproduct gypsum needs more heat source, more advanced energy saving and environmental protection  production  technology. By research and production practice for many years, we have developed energy saving and environmental protection two-step process industrial byproduct gypsum production line, making technical breakthrough on production line processing,  drying, crushing, calcination, grinding, aging, heat source and control of various systems; indexes of product quality reach or exceed natural gypsum powder with same indexes.

Production line features:

1. Civil work and equipment support adopted steel structure type, has various features such as short construction period, less investment and small floor area,  and saves over 60% of fund than traditional civil works; construction period of production line  with annual output below 100,000 tons is 75  working days; construction period of production line  with annual output over 1,000,000 tons is 150 working days;

2. The company has three-cylinder drying, fine calcination, grinding, gasifying and aging patent technology, customized design according to raw materials at different areas and performances of later products, and uses NE plate chain hoister and energy saving three-cylinder drying machine and air trough conveyor, full use of calcination remaining heat, energy saving and equipment, saving energy consumption index over 15%;

3. Adopting medium temperature and low  temperature calcination technologies, heat exchange area of calcination equipment is 1.4 times of that of natural gypsum calcination equipment, and the product quality indexes are ideal. Production line uses DCS automatic control technology, which has  high automatic degree , stable quality and labor saving;

4. The whole line makes negative pressure operation, drying, calcination dust collection uses three-level dust collection system, tail discharge after treatment <30 mg/m3, environmental protection meets environmental protection standard in various areas;

5. Partial equipment of production line use special material such as 20g, 16Mn, 40Cr and SS304; equipment paint selects high temperature and anti-corrosive special painting, and each equipment uses sand blasting antisepsis measures, which ensure operating life of the whole production line;

6. With specialized installation, training and adjustment team and short installation  period of the whole line, the company has unique production line calcination “0” adjustment expense, which saves large investment to new  enterprise.

Flow chart:

Technical index