Calcium Chloride Dihydrate Granule
1.Material properties
Calcium chloride dihydrate is hydrated inorganic salt with the chemical formula CaCl₂·2H₂O, also known as crystalline calcium chloride or industrial calcium chloride dihydrate. It appears as a white or grayish-white granular, flaky, or lumpy solid. Its density is 2.15 (25℃), melting point is 782℃, and boiling point exceeds 1600℃. It is highly hygroscopic, readily deliquescing when exposed to air, releases heat when dissolved in water, and its aqueous solution is slightly alkaline.
This substance is mainly produced through the purification and concentration of ammonia-soda process waste liquid or by reacting hydrochloric acid with limestone. Its main applications include de-icing agents, antifreeze, food coagulants, calcium fortifiers, and rubber coagulants. Industrial applications include construction, textiles, and metallurgy. The product requires a calcium chloride content of ≥68%. It should be stored in a cool, dry environment, and protective equipment must be worn during handling to avoid dust inhalation or skin contact.
2. Process Introduction
Based on market demand for dihydrate granular calcium chloride and considering the physical properties of calcium chloride itself, our company has conducted extensive research and development, and through small-scale and pilot-scale experiments, successfully developed a rotary granulation system with high capacity, low energy consumption, and a longer operating cycle. We have secured commercial contracts, achieved successful start-up on the first attempt, and received engineering case validation, earning unanimous praise from our clients. We have also obtained Chinese and international invention patents.
The dihydrate granular calcium chloride production unit mainly includes an evaporation section and a rotary granulation section.
1）Evaporation Section: Low-concentration calcium chloride solution first enters the evaporation system, where it is evaporated to over 69% using a multi-effect evaporator, and then sent to a rotary granulator for granulation. Secondary steam from the evaporation system is cooled and recovered by a surface cooler for centralized treatment. The condensate from the live steam is returned to the boiler room for reuse.
2）The finished 69% calcium chloride solution from the evaporation section is pumped into a rotary granulator. Inside the rotary granulator, it is atomized by nozzles, adheres to the surface, and is dried to complete the granulation and drying process. After sieving and cooling, the qualified product is obtained. The granulation and drying exhaust gas undergoes two stages of purification and dust removal—a cyclone dust collector and a wet scrubber—to meet emission standards before being discharged.
3.Technical Advantages
1）Evaporation section
A. The evaporation section has mature technology, stable operation, and can meet the evaporation needs of calcium chloride stock solution of different concentrations. It is also easy to operate.
B. To address the issue of strong chloride ion corrosiveness in calcium chloride solutions, key equipment and components are made of chloride ion-resistant materials, such as TA9 and TA10, to reduce equipment maintenance frequency and ensure equipment lifespan.
C. This invention solves the technical challenge of long-distance transportation of high-temperature, high-concentration calcium chloride solutions, ensuring that the calcium chloride solution does not cool down, crystallize, or become blocked during transportation, thus ensuring a continuous and stable transportation process.
2)Rotary granulation section
a. Groundbreaking technology has been developed to produce dihydrate granular calcium chloride using a rotary granulator, extending the operating cycle to 180 days compared to the 7-10 day operating cycle of a fluidized bed granulation system.
b. The rotary granulation process innovatively utilizes the cooling and crystallization properties of high-concentration calcium chloride, releasing a large amount of heat. Inside the rotary granulator, the material cools, crystallizes, and granulates, then the heat released during crystallization is used for drying. Compared to other high-temperature drying granulation processes, this process reduces steam consumption by 60%.
c. Cyclone is used for primary coarse separation, followed by secondary separation by a wet dust collector, achieving a fine powder recovery rate of over 99 %, ensuring high material yield and meeting environmental emission standards.
d. Thanks to the reduced heat demand of the rotary granulation system, the amount of drying medium in the system is reduced, the load on the exhaust gas treatment system is reduced, and the equipment investment is lowered.
e. The atomizing nozzle developed for high-concentration calcium chloride solutions makes the calcium solution atomized more uniformly and stably, resulting in smoother granulated product surfaces, more uniform particle size, and higher product quality.
3) Control
a. It integrates complete DCS control logic, enabling fully automated operation from feeding, evaporation, drying to discharging, and supports preset and automatic switching of multiple process parameters.
b. The system collects and displays key process parameters such as feed rate, heat medium temperature , medium flow rate, and system differential pressure in real time. The system is automatically adjusted in a chain, and the system operates stably on its own, ensuring a stable and controllable production process.
