The construction gypsum powder production line using phosphogypsum as raw material adopts a one-step production process of co-current rotary kiln drying and calcination, and uses coal-fired flue gas hot air furnace as the heat source, that is, crushing, drying and calcining of phosphogypsum in the rotary kiln Once completed, the inlet temperature of the drying and calcining device is controlled at 800°C and the outlet temperature is 170°C.
Phosphogypsum Drying and Calcining Plant

1. Problems existing in phosphogypsum drying and calcining device

(1) Unstable drying quality The integrated drying and calcination production line is a medium-speed calcination process. Due to factors such as large fluctuations in raw material moisture and unstable fuel control, the phase composition of the product is unreasonable, which is far from satisfying the gypsum production line for gypsum powder. Quality requirements. As a result, the use range of gypsum powder is small, and there are many quality problems, which affect the normal sales of gypsum powder.
(2) Small output and high production energy consumption Due to the integration of drying and calcination, the drying and calcination time is short. The amount of phosphogypsum treated per hour is only 18-20 tons on dry basis and 26 tons on wet basis (500-550 tons per day). The output is about 150,000 tons, and the design capacity is not up to 200,000 t/a. Due to the small output of dry gypsum powder, the coal consumption is up to 85kg/t, which is much higher than that of the two-step method in the tube industry (about 65kg/t).
(3) There are agglomerates in the phosphogypsum slag of poor calcination quality, which easily enters the drying section through the grate and belt during the feeding process, causing lumps in the drying and calcination process, the outer layer is over-fired, and the inner layer is under-fired Happening. Due to the presence of lumps, the feeding of gypsum powder is unstable, and it is not easy for the operator to adjust the calcination temperature according to the amount of feeding in a short time, and it also causes uneven calcination of the gypsum powder.

2. Technical reform measures

According to the above problems, focus on the adjustment of the number of plate copying, lifting angle, material filling factor, etc. of the drying and calcining device, so that the material can fully contact with the heat source, extend the material drying and calcining time, ensure product quality, and increase output. The following transformation plans were determined.
(1) Add 3 baffle rings (high 300㎜) at different positions in the cylinder of the drying section to increase the filling factor of the material in the drying cylinder, and increase the filling factor from 4% to 15%. Under the premise of the device load, the total amount of dried materials is increased by 20m³, and the distribution of materials is balanced, and the thermal conductivity of the materials is improved.
(2) Change the copy board from 16 pieces per circle to 30 pieces per circle to make the material distribution of the barrel section more even.
(3) Both sides of the original copy board are open, no blocking board is added, and the material is reduced during lifting. Due to the small amount of lifting material, the material moves quickly backwards in the case of silver powder drying, causing the material to lift. all. For this reason, a blocking plate (the rear side of the machine) is added at the rear end of the copy board to prevent the material from moving backward quickly and the material of the barrel section from being uneven.
(4) Drawing lessons from the inspection experience, add 3 groups of cross structures in the drying section cylinder, each group is 2 meters long, further increase the heat exchange area and improve the heat exchange efficiency.
(5) Increase the number of hitting chains at the feed end of the drying and calcining device to make the gypsum powder agglomerate completely pulverized, to avoid the internal under-burning and external over-burning caused by large particles.
(6) Increase the vibration motor of the existing feeding hopper, improve the vibration effect, and stabilize the discharge volume.
(7) The raw material feeding belt is changed to a belt scale or a screw scale for measurement, so that the cutting amount is stable and accurate.

3. The effect of technical transformation of the production line of phosphogypsum drying and calcining device for building gypsum powder

(1) The quality of gypsum powder is improved. The composition of gypsum powder phase is very stable and reasonable, and the setting time and strength are improved.
(2) The output of gypsum powder has been increased. The daily output of gypsum powder of the device has increased by more than 100 tons compared with the original one, which has reduced coal consumption and reduced the cost by about 30 yuan per ton of gypsum powder.
(3) The improvement of the quality of construction gypsum powder increases sales, improves customer satisfaction, reduces quality disputes, and improves the company's credibility.

Shanghai Clirik Machinery Co.,Ltd. specializes in the production of grinding mills and crushers and related equipment, and has independently developed ultrafine mills, micro powder mills, and new Raymond mills. It can be used to process 50-3000 mesh powder. Welcome to online consultation.