1. Material characteristics:

Lithium hydroxide monohydrate is a white crystalline powder. Soluble in water, slightly soluble in alcohol, can absorb carbon dioxide from the air and metamorphism, was strongly alkaline. It will not burn, but it is highly corrosive. Usually in the form of a water. When the temperature is higher than 100 ℃, the crystal water is lost, and lithium hydroxide generates lithium oxide and water vapor at about 1000 ℃. Lithium hydroxide monohydrate is one of the most important lithium compounds. It is mainly used to produce lithium-based greases, and can also be used to produce other lithium compounds. It is an additive for alkaline battery electrolytes. The main raw materials for the production of lithium hydroxide monohydrate are lithium mica, spodumene, salt lake brine and so on.

Lithium hydroxide monohydrate is a white crystal with poor fluidity. The water content of wet materials from the previous centrifugal process is generally about 3%, and the water content of the product after drying is required to be less than 0.5.

2. Special drying process:

Lithium hydroxide monohydrate drying has the following characteristics and requirements: the heating temperature is low (generally 80-95 ℃ hot water is used), and the crystal water is easy to be removed when the temperature is high; In the process of material drying, carbon dioxide is easy to react and denature, so the drying equipment needs to be airtight operation. The material is loose, but the fluidity is not good and easy to scar. It is required to have low energy consumption, uniform heating, good operating environment and meet the index requirements; battery-grade lithium hydroxide monohydrate requires strict addition of magnetic substances in the drying process (generally <30ppb).

Hebei Yanming Chemical Equipment Co., Ltd. has successfully used energy-saving and environment-friendly disc continuous dryer as lithium hydroxide monohydrate drying equipment according to material analysis and many years of engineering experience, and has provided drying system solutions for many manufacturers of this material.

In view of the requirements of lithium salt and battery material industry for magnetic substances after drying (generally within 30ppb), our company took the lead in proposing to change the contact material parts (such as cloth tray, drying tray, inlet and outlet, rake leaf, etc.) of disc continuous dryer from stainless steel to titanium and non-metal, and designed and reformed the drying equipment of many battery material manufacturers. If the magnetic material of the product after drying is not strict, the equipment material can choose 304 stainless steel or 316L stainless steel.

The wet material of lithium hydroxide monohydrate transported from the previous process is continuously and quantitatively added into the energy-saving and environment-friendly disc-type continuous dryer by the quantitative feeder for drying operation. The material completes the heat and mass transfer process in the flow process to achieve the purpose of drying. After the dry material is cooled in the dryer to reach the packaging temperature (generally about 50 ℃), it is discharged from the discharge port at the bottom through the discharge rotary valve and enters the next process. The tail gas escaping from the material is discharged from the wet discharge port at the top of the dryer after dust removal by a special dust collector.

3. Process characteristics:

① In view of the characteristics that lithium hydroxide monohydrate is easy to react with carbon dioxide, first, a closed disc continuous dryer is used for drying to avoid the reaction of lithium hydroxide monohydrate with carbon dioxide during the drying process. Secondly, an air closure is provided at the discharge port of the disc continuous dryer to avoid the introduction of a large amount of cold air due to the suction effect of the fan. Thirdly, a special structure is adopted to prevent lithium hydroxide from reacting with carbon dioxide in the air, and specific measures are reflected in the final equipment.

Continuous operation, high thermal efficiency. Since the disc continuous dryer is dried by conduction and heat transfer, air is not allowed in the dryer during the drying process, and its tail gas carrying capacity is very small, so its thermal efficiency can reach more than 85%;

③ Less material loss and good operating environment. In the drying of lithium hydroxide monohydrate in the disc continuous dryer, because the materials go in and out, the distribution of the materials is wet and dry, and the flow rate of the drying tail gas is extremely low (about 0.1 m/s), the material dust is difficult to float to the top of the equipment and is rarely carried away by the tail gas, which not only does not lose the materials, but also does not pollute the environment, thus meeting the requirements of environmental protection. The whole drying system is airtight operation, can recover more than 99% of the dust;

The adjustable equipment, material drying uniform adjustable. The effect of material drying can be conveniently adjusted by adjusting the speed of the equipment, adjusting the thickness of the material layer, the flow rate of the heat source, the temperature of the heat source, the number of rake arms, the form, size and angle of rake leaves, the amount of material added and the number of drying trays in the dryer;

⑤ Stable operation, long service life and simple operation of the equipment;

The material flow direction is single, no backmixing phenomenon, uniform drying, stable quality, no need to remix;

⑦ Each layer of drying tray can be separately introduced into the heat medium or cold medium to heat or cool the materials, and the upper part of the drying and lower part of the cooling can also be realized in one device, and the temperature control of the materials is accurate and easy;

⑧ For the small particles in the wet material, the special crushing device is added to the appropriate position inside the dryer, so that the crushed small particles are powder, which can strengthen the heat transfer and drying process and ensure the uniformity of the dry material;

⑨ Easy installation, small footprint. The dryer is delivered as a whole and transported as a whole. It only needs to be hoisted in place, and the installation and positioning are very easy. Due to the layer-by-layer arrangement and vertical installation of the drying tray, even the drying area is large and the floor area is small.

⑩ In view of the requirements of the battery material industry for magnetic substances after drying (generally within 30ppb), our company took the lead in proposing to change the direct contact material part of the disc continuous dryer from stainless steel to titanium, and designed and reformed the drying equipment of many battery material manufacturers to meet the requirements of the final customer.

In view of the problem of dust and odor in the exhaust gas of lithium hydroxide monohydrate drying process, a wet dust collector with better dust removal and odor removal is used to remove the dust and odor in the exhaust gas.

The patented technology (utility model patent, patent number: ZL2016212122004) is used to separate the drying area from the cooling area in one device, isolating the diffusion of moisture from the drying area to the cooling area, and preventing the moisture from condensing and increasing the humidity of the dried material. At the same time, the opening is set so that the material can pass through to ensure normal operation.

In view of the problem that lithium hydroxide has poor fluidity and has scarred on the drying plate surface, a special rake rod structure is adopted so that the material will not scar on the drying plate.