Significance and Methods of Mineral Dehydration
Dehydration is the process that remove water from the solid material containing moisture.
In the beneficiation process, the vast majority of beneficiation products contain a lot of water. For example, the concentrate Flotation plant get contained moisture approximately 4 to 5 times the solid weight , the concentrate obtained from the re-election plant and the magnetic separation plant concentrators also have a lot of water. Therefore, the dehydration is necessary , otherwise, the concentrate transportation will be very difficult, and the transportation costs will increase. in the cold regions, the water contained in the mine concentrate will froze. The concentrate dewatering is also very necessary for the smelting of the concentrate ,at the same time ,the mine dehydration is very important to the smelting, the large amount contained water not only increase the energy consumption of smelting, but also reduces the utilization factor of the metallurgical furnace. In addition, in order to strengthen environmental protection, or in order to reduce fresh water consumption in areas of water scarcity ,the beneficiation products dehydration is essential.
The tailings water content are often more than 70% , in general, before the tailings are sent into the tailings pond,they must go through the dehydration process.
It is thus clear that the dehydration operation is an
important part of the the beneficiation production .
The commonly used dehydration methods are the following:
◆ mechanical
dewatering
It is a method that use the mechanical force (gravity, pressure,
centrifugal force) to separate the water and solids . Such as precipitation
concentrated, filter are all fall into this category. The main application of
beneficiation production dehydration are these methods.
◆ thermal
dehydration
It is a method that use the thermal energy to vaporize the
water and then achieve the purpose of separating water and solids. such as the
rotary kiln
dryer drying falls into such category.
◆ physical chemical methods
dehydration
It is a method that use the water-absorbent chemicals, such as
lime, anhydrous calcium chloride to absorb moisture from the material.
In
the beneficiation process, the dehydration of the coarse material is
relatively simple, we can only use the gravity to make the materials moisture
dry, so most of the water will be removed. but the dewatering of fine-grained
material is more complex, such as the flotation plant concentrates, average
particle size are relatively thin, its dehydration is usually divided into two
steps: The first step : settlement concentrated, use the common sedimentation
tanks or concentrated machines and other equipment, concentrate the very dilute
slurry to the pulp whose water content is only 50-80%; the second step:filter,
filter the concentrate product's moisture to16-8 percent. Depending on the
actual circumstances, in particular, the north cold season when the concentrate
moisture requirements are strictly , sometimes the third step dry dryer is
necessary. Dry the materials by dry machine, which can reduce the materials
water down to 6% or less. However, it must be pointed out that the drying and
dehydration cost is high , and the concentrates loss is large. So the commonly
used processes in the concentrator are the enrichment ,filter these two-stage
dehydration processes.
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