Mechanical vapor recompression (MVR) reduces external steam consumption by recycling secondary vapor and is widely used for concentrating lithium precipitation mother liquor and reducing the volume of high-salinity wastewater in salt lake lithium extraction projects. Many projects procure high-performance MVR equipment as a standalone solution, only to encounter heat transfer surface scaling, salt buildup and blockages in pipelines, and frequent shutdowns for cleaning after commissioning, resulting in lower-than-expected capacity and returns. Industry experience indicates that a well-designed mother liquor recovery system can increase overall lithium recovery from a salt lake project by 12%–18%. As salinity continues to change during the evaporation of high-salinity mother liquor, calcium, magnesium, silica, and suspended solids can readily accumulate and form deposits. The long-term stability of MVR operation depends not on the rated specifications of individual equipment, but on feedwater quality control, process operating limits, and system-wide integration.
The primary role of pretreatment is to establish stable feed conditions for the MVR evaporation system and reduce scaling risks at the source. Suspended solids, calcium and magnesium hardness, and silica in salt lake mother liquor are major causes of equipment blockage, making it necessary to develop purification solutions tailored to actual water quality. Concentrate streams and regeneration waste liquids generated by purification units such as membrane separation and ion exchange must also be incorporated into the overall treatment plan. By consistently controlling key feedwater parameters, scaling on evaporator surfaces can be significantly reduced, helping ensure continuous production. Drawing on BICHEM’s engineering experience, when water quality adaptation and coordinated system design are properly addressed, an MVR system can achieve stable operation for 60–90 days per cycle, reducing production losses and operating and maintenance costs associated with shutdowns for cleaning.
Evaporation and crystallization should not be designed as separate stages, but rather planned and managed as an integrated system. In high-salinity systems, boiling point elevation, changes in viscosity and salt solubility, and crystallization ranges all affect heat transfer efficiency, energy consumption, and the risk of blockages. Blindly pursuing higher concentration ratios while overlooking salt saturation, crystallization locations, and flow channel design can instead exacerbate scaling and deposition. Therefore, the evaporator configuration, circulation flow rate, operating temperature, heat transfer area, and final concentration point must all be determined according to material properties and treatment objectives.
For projects primarily focused on mother liquor concentration, the evaporation endpoint should be controlled appropriately to avoid operational risks associated with excessive concentration. For projects requiring further salt separation or zero liquid discharge (ZLD), crystallization, solid-liquid separation, mother liquor recycling, and residue treatment must be planned as an integrated process. An efficient mother liquor treatment system is not simply the sum of individual equipment specifications, but the result of coordinated optimization across pretreatment, evaporation, crystallization, and mother liquor recycling.
For project owners, the purchase price of MVR equipment is only one component of the investment decision; lifecycle costs ultimately determine long-term returns. Electricity consumption, supplementary steam, cleaning-related downtime, equipment maintenance, chemical usage, membrane replacement, and mother liquor disposal all have a continuing impact on system economics. Industry data indicates that operating costs often account for more than 60% of the total lifecycle costs of MVR-related systems. Project assessments should therefore move beyond comparisons of individual equipment and focus on the entire process, with particular attention to feedwater quality stability, pretreatment capacity, coordination between evaporation and crystallization, the monitorability of key operating parameters, and the ease of cleaning and maintenance. Since water quality and process conditions vary from project to project, energy consumption, treatment capacity, and operating cycles should be evaluated based on actual water quality and system design rather than by simply applying performance figures from other projects.
BICHEM specializes in salt lake lithium extraction processes and full-process system integration, helping customers transform MVR from a standalone evaporation unit into a stable, controllable, and economically viable long-term treatment system. For lithium precipitation mother liquor and other process streams, as well as high-salinity wastewater, BICHEM can assess upstream impurity removal solutions, optimize MVR operating conditions, coordinate crystallization and salt separation, and evaluate lifecycle economics based on water quality characteristics, lithium recovery targets, environmental requirements, and project-specific conditions. From controlling feed parameters and coordinating evaporation and crystallization to managing mother liquor recycling and residue treatment, BICHEM applies a systems engineering approach to reduce process integration risks and help customers achieve a more effective balance between operational reliability, energy efficiency, and long-term economic performance.
