Dehydration screen is a key equipment for reducing the moisture content and
recovering fine sand after washing quartz sand with water. If the dehydration
effect is poor (the moisture content of the finished product exceeds 15%) and
the loss of fine sand is high (the loss rate of<0.1mm fine sand exceeds 8%),
it will increase the drying load, waste raw materials, and affect subsequent
storage and transportation. Based on extensive project experience, summarize a
three-step troubleshooting method to quickly restore equipment performance.
Step 1: Check the sieve and vibration system - the core components determine
dehydration and recovery
Improper selection of screen mesh or deviation in vibration parameters are
the main reasons.
The mesh size of the sieve is incorrect or blocked: if the mesh size is too
small (such as 20 mesh), fine sand will be lost with the wastewater; Excessive
mesh size (such as 100 mesh) makes it difficult to remove water and results in
high moisture content. It is recommended to use a 40-60 mesh polyurethane sieve
for dehydration of quartz sand, which has good permeability and wear resistance.
If the sieve is clogged (fine mud adheres), it needs to be washed with a
high-pressure water gun (0.6MPa), or a dispersant (0.1% sodium
hexametaphosphate) should be added before feeding to prevent adhesion.
Insufficient vibration frequency or amplitude: If the frequency is below
18Hz, the material will bounce weakly and moisture will be difficult to detach;
The amplitude is less than 2mm, and fine sand is prone to accumulate on the
screen surface and cannot be discharged with vibration. Use a vibration tester
to detect and adjust to a frequency of 20-25Hz and an amplitude of 3-5mm. Use a
frequency converter or eccentric block to ensure that the material undergoes
"high-frequency light jumping" dehydration and dispersion.
Step 2: Calibrate operating parameters - parameter imbalance amplification
problem
Improper settings of feed rate, screen inclination angle, and flushing water
directly affect the effectiveness.
Overloading or uneven feeding rate: exceeding the rated processing capacity
(such as 30t/h, actual 40t/h), material accumulation on the screen surface
exceeding 5cm, and difficulty in penetrating moisture; The amount of feed
fluctuates greatly, and the dehydration effect fluctuates greatly. Use an
electronic belt scale to control the amount and maintain it at 80% -90% of the
rated value. Install a fabric dispenser to evenly distribute the material on the
screen surface and avoid local accumulation.
Unreasonable inclination angle of screening surface: inclination angle less
than 5 °, slow material flow, and prolonged retention of moisture; Greater than
12 °, the material slides rapidly and the dehydration time is insufficient.
Adjust the protractor to 7 ° -10 °, taking into account both flow rate and
dehydration time. After adjustment, observe the moisture content of the
discharged material and gradually adjust it to the optimal state.
Improper flushing water pressure: if the pressure exceeds 0.4MPa, it is easy
to wash away fine sand; Below 0.2MPa, it is difficult to clean the adhesive mud
powder on the sieve mesh. Install a pressure regulating valve to control the
pressure between 0.25-0.3MPa, and use a fan-shaped nozzle to evenly spray water
to reduce the loss of fine sand.
Step 3: Adaptation of materials and daily maintenance - raw material
issues+maintenance deficiencies hinder progress
Inadequate material characteristics and maintenance can exacerbate equipment
issues.
High mud content or uneven particle size of materials: if the mud content
exceeds 10%, the mud powder will clog the sieve, making it difficult to
discharge moisture; Coarse particles (>2mm) are mixed with fine particles,
and fine particles are easily carried away by coarse particles. Pre screening is
required before dehydration to separate coarse and fine particles; When the mud
content is high, add a washing process to reduce the proportion of mud
powder.
Maintenance deficiency: Aging of supporting springs (30% decrease in
elasticity), weak vibration transmission; The lack of oil in the bearing leads
to unstable speed. Check the spring status weekly and replace it every 3 months;
Check the bearing temperature daily (≤ 65 ℃), add lithium based grease weekly,
clean the screen mesh and residual materials in the machine every month to avoid
component wear.
By following the above three steps, the moisture content after dehydration
can be reduced to below 8%, and the loss rate of fine sand can be controlled
within 3%. If there are still problems, it is recommended to contact the
manufacturer to test the compatibility of the equipment and ensure accurate
matching with the production needs of quartz sand.