Phosphogypsum powder production line
- Categories:Production Line
- Time of issue:2019-05-09 00:00:00
Using phosphogypsum as raw material
Production: 10,000 tons to 800,000 tons per year
Phosphogypsum is the solid waste of the phosphate fertilizer industry, and phosphoric acid is the foundation of the phosphate fertilizer industry. The production process of wet phosphoric acid is to decompose phosphate rock powder with sulfuric acid to generate extraction slurry, and then filter and wash to obtain phosphoric acid. Phosphogypsum waste is also generated in the process of filtration and washing. Generally, about 5-6 tons of phosphogypsum are produced for every ton of phosphoric acid produced, and 2.5-5 tons of phosphogypsum are produced for every 1 ton of diammonium phosphate produced. The output of wet-process phosphoric acid in my country is about 1 million tons. With the rapid development of high-concentration compound fertilizer industry in my country in recent years, nearly 20 million tons of phosphogypsum are discharged from phosphate fertilizer chemical enterprises every year.
Phosphogypsum is generally in the form of powder, and it is in the form of a slurry because it contains 8-15% of the attached water. The particle diameter is generally 5-150µm, and its main component is CaSO4•2H2O, which can generally reach 70-90 %, the secondary components contained in it vary with the source of the ore, and the components are more complex, generally containing rock components, Ca, Mg phosphates, carbonates and silicates, in addition, also contains a small amount of Organophosphorus, sulfur, fluorine compounds. The appearance of phosphogypsum is generally gray, gray, gray-yellow, light yellow, light green and other colors, the relative density is 2.22---2.37, and the bulk density is 0.733---0.880g/cm3.
Phosphogypsum is different in its composition, color, physical properties, impurity content, impurity type, etc. due to its different manufacturers, but they all have the following common characteristics:
1. Most of the phosphogypsum has high attached water, which is discharged in the form of slurry or wet slag. Generally, the content of the attached water is 10-40%, and some are even higher.
2. The particle size of phosphogypsum is relatively fine, and the particle size is generally between 5-300 microns. When producing gypsum powder, it can save the cost of crushing and grinding, but it will also generate a large amount of dust and increase the cost of dust removal.
3. Phosphogypsum generally contains more complex components, chemical components that are small in content but have a great impact on the hydration and hardening performance of gypsum, and the pH value is acidic rather than neutral. It brings great difficulty to the effective utilization of chemical gypsum.
In phosphogypsum, the content of active ingredient dihydrate gypsum is generally high, up to 75-95%, which is equivalent to the active ingredient content of gypsum above the second grade. If only considering the content of its active ingredients without taking into account the influence of its harmful impurities, the industrial by-product gypsum can be used as a high-quality raw material for gypsum production.
Therefore, the use of suitable technology and equipment can eliminate the influence of harmful components in phosphogypsum, and phosphogypsum will become a cheap, high-grade, and environmentally friendly high-quality production raw material. The two-step calcination production process of raw material pre-drying and boiling furnace combustion is adopted, and the raw material is transported from the yard to the hopper by the loader. After breaking machine, belt conveyor. It is evenly sent to the rotary dryer (the heat source here is a coal-fired hot blast stove), and after discharging, it is transported to a vertical boiling furnace for calcination (the heat source here is a heat-conducting oil furnace), and then sent to a ball mill for calcination. Grinding, modification and cooling, and then transported to the finished product warehouse and packaging warehouse.
Calcination system: vertical boiling furnace process:
Simple structure and small footprint
No moving parts, low operating cost
Due to the thorough fluidization of the production process, the composition of the plaster of paris is ideal and the product quality is stable.
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