Lithium wastewater evaporation treatment process

Lithium wastewater evaporation treatment process

In the past few years, as the new energy vehicles continue to grow at a high rate, the battery industry continues to boom, the battery market has driven the demand for materials to continue to grow. At the same time, the rapid development of the industry has also brought many problems, mainly in the supply of raw materials.In recent years, the prices of major raw materials, including nickel, cobalt and lithium, have risen rapidly, resulting in an overall shortage of nickel, cobalt and lithium materials due to excessive demand growth and various factors such as environmental protection.

In this industry context, a large number of new products have been launched, ternary precursor products. Lithium carbonate. Lithium hydroxide. Manganese sulfate. Cobalt sulfate. Nickel sulfate and other raw materials manufacturers have expanded production to meet the future market demand.

Water quality characteristics of the lithium industry.

Evaporation crystallization treatment process for lithium industry.

In LiCO3, LiOH production, LiSO4 leached by lithium pyrochlore acid has to be concentrated by distillation to a certain concentration before it can be used to precipitate LiCO3. LiOH crude and LiOH also need to be obtained by evaporative crystallization and secondary evaporative crystallization. Similarly, the last step in the production process of NiSO4, CoSO4, and MnSO4 is evaporation crystallization and drying.

Evaporation crystallization treatment process for lithium industry.

Lithium wastewater, especially the wastewater after LiCO3 precipitation, mainly sodium sulfate, high sodium sulfate content close to saturation, high COD content in the wastewater, and contains a small amount of fluorine ions about 200mg/L, fluorine ions affect the evaporation equipment selection, before entering the evaporation can be added calcium chloride using chemical precipitation method to precipitate most of the fluorine ions, after, into the evaporation equipment evaporation crystallization desalination, distilled water Go to biochemical treatment to meet the standard discharge. Evaporation equipment is recommended to use the energy efficient MVR form

MVR principle:

MVR stands for Mechanical Vapor Recompression, an energy-saving technology that reuses the energy of the secondary steam it generates to reduce the need for external energy.The working process of MVR evaporator is to compress the steam at low temperature level by compressor, the temperature and pressure will be increased and the enthalpy will be increased, then it will enter the heat exchanger to condense in order to make full use of the latent heat of steam.The secondary steam from the evaporator is compressed by the compressor, the pressure and temperature rise, and the enthalpy increases, and then it is delivered to the heating chamber of the evaporator as heating steam to maintain the boiling state of the liquid, while the heating steam itself condenses into water, so that the steam is fully utilized.

The MVR evaporation process flow chart is as follows:


Process Description:

1) Material System

Raw water tank (pool) → feed pump → preheater → MVR forced circulation evaporation system → discharge pump → crystallization tank → centrifuge → solid wet salt

Evaporation system adopts forced circulation process, configuring a forced circulation pump, in order to ensure that the material in the column tube full tube flow at high speed, to prevent material scaling plugging tube. Forced circulation process features are as follows:

Forced circulation evaporators are used in conditions where scaling or crystallization is avoided by boiling on the heating surface.

The circulation of forced circulation evaporation solution in the equipment mainly relies on the circulation pump to produce forced flow.

The material does not evaporate in the heater and will not undergo concentration changes. The concentration will only increase after flashing in the separation crystallizer, so it will not adhere to the heat exchange surface and cause heat exchange surface scaling.

The separation body has a very adequate liquid/gas separation area and separation height, which can ensure stable evaporation volume and discharge concentration over a long period of time.

Energy consumption for operation: the feeding volume: 8335kg/h, evaporation volume 5500kg/h case, steam unit price according to: 260 yuan/t, electricity price according to 0.7 yuan/kw, converted operating costs.

IV. Economic analysis
Gas consumptionTotal150kg/hElectricity consumptionRun298.405kW/h
Water consumptionTotal80t/hGas consumptionTotal15Nm3/h
Water consumptionBy evaporation¥47.37Yuan/t    
By processing capacity¥31.54Yuan/t    
8000h run¥2,103,068.00Yuan/y    
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