The dehydration process in mineral processing is a crucial step in removing moisture from ores or concentrates, aiming to reduce transportation costs and meet the requirements of subsequent smelting or sales.
The dehydration process is usually carried out in stages based on the particle size of the material, moisture content and product requirements. The following are the main steps and common processing procedures:
Three Stages of the dehydration process
1.Concentration (gravity dewatering)
Principle: Utilizing gravitational sedimentation to separate solid particles from the suspension.
2. Filtration (mechanical dewatering)
Principle: Water is forcibly separated by pressure difference (vacuum or pressure filtration).
Effect: The moisture content is reduced to 10%-20%.
3.Drying (thermal dehydration)
Principle: Heat and evaporate the remaining water, which is used for concentrates with strict moisture requirements (such as pretreatment before smelting).
Effect: The moisture content can be reduced to below 5%, but it has high energy consumption and is usually used in the final product.
4.Typical Dehydration Processing Procedures
Coarse-grained ores (such as placer ores and coal)
Process: Screening and dewatering → Centrifugal dewatering (optional) → Natural drying
Equipment: Vibrating screen, dewatering screen, spiral classifier.
Characteristics: Coarse particles are easy to dehydrate and usually do not require filtration or drying.
Fine-grained concentrates (such as iron concentrate, copper concentrate)
Process: Concentration → Filtration → Drying (optional)
Example: Iron ore flotation concentrate: thickener → disc vacuum filter → rotary dryer (moisture content reduced from 80% to 8%).
Clay minerals: A high-pressure filter press may be needed to replace vacuum filtration.
Tailings treatment
Process: Concentration → Deep cone paste concentration → Pressure filtration/Tailings dry stacking
Objective: To reduce the water volume of the tailings pond and enhance safety (such as using ceramic filters to lower the moisture content of tailings to below 15%).
Overall, the dehydration process in mineral processing is a crucial step that gradually reduces the moisture content of the material through three stages: concentration, filtration, and drying, ultimately meeting the requirements for transportation, storage, or smelting. The core lies in choosing the appropriate technical combination based on the characteristics of minerals (particle size, viscosity, moisture requirements), and achieving a balance among efficiency, cost and environmental protection.
