Heavy duty vibrating screen is a key grading equipment for large-scale quartz
sand production lines (daily processing capacity ≥ 3000t), responsible for
grading crushed quartz sand into specifications such as 20-40 mesh and 40-70
mesh (requiring screening efficiency ≥ 90% and screen service life ≥ 15 days),
directly affecting the quality of finished sand and the connection with
subsequent processes. If the screening efficiency is low (less than 75%) and the
screen mesh is frequently damaged (with a service life of less than 7 days), it
will cause unqualified sand to mix into the finished product, increase the
frequency of equipment shutdown, and restrict the production line capacity.
Based on the characteristics of high hardness of quartz sand and large equipment
load, a three-step troubleshooting method is summarized to quickly restore
screening performance.
Step 1: Optimize the screening box structure and screen configuration - the
core components determine the screening effect
The main reasons for low efficiency and easy breakage of the screen mesh are
the mismatch of screen material, insufficient rigidity of the screen box, or
improper tensioning method.
Poor adaptability or poor fixation of the screen mesh: ordinary low-carbon
steel screen mesh is selected, which has poor wear resistance and is prone to
cracking when facing quartz sand impact; Insufficient tension of the screen mesh
(tension<8kN/m), increased friction with the screen frame during vibration,
and premature tearing of the edges; The deviation of the sieve aperture exceeds
5%, and the grading accuracy is out of control. Replace the quartz sand specific
polyurethane composite screen mesh (with 5 times the wear resistance of ordinary
steel mesh), and accurately match the pore size according to the target particle
size; Adopting a dual tensioning structure of "bolt+wedge block", the tension is
tested with a tension meter after tensioning to ensure that the tension is
stable at 10-12kN/m and avoid movement during vibration.
Insufficient rigidity or vibration imbalance of the screening box: The
thickness of the side plate of the screening box is less than 16mm, which is
prone to deformation during long-term high load operation, resulting in the
tilting of the screening surface; The installation of the exciter is not
synchronized, and the vibration phase deviation exceeds 5 °. The screen box
shows twisted vibration, exacerbating the damage to the screen mesh. Reinforce
the screening box and install reinforcing ribs on the side panels to ensure that
the stiffness meets the standard; Calibrate the installation position of the
exciter, adjust the phase difference to 0 °, and monitor the amplitude of the
sieve box with a vibration detector to ensure that the amplitude deviation on
both sides is ≤ 0.5mm.
Step 2: Calibrate excitation parameters and feed control - precise control to
improve efficiency
Insufficient excitation force, inappropriate frequency, or abnormal feeding
can exacerbate screening problems.
Unbalanced excitation parameters: The excitation force is less than 150kN,
which cannot effectively overcome the gravity and friction of quartz sand,
causing fine sand to remain on the screen surface; Vibration frequency below
12Hz, slow material layering speed; Above 18Hz, the screen is subjected to
excessive impact and is prone to fatigue damage. By adjusting the angle of the
eccentric block of the exciter, the excitation force is controlled at 180-220kN,
and the vibration frequency is calibrated to 14-16Hz. Dynamic adjustments are
made according to the feed rate, and the excitation force is appropriately
increased when processing large quantities to ensure rapid material
stratification.
Overloaded feed rate or uneven fabric distribution: The feed rate exceeds the
rated value (such as 200t/h, actual 250t/h), the stacking thickness of the
screen material exceeds 150mm, and the lower layer material cannot contact the
screen mesh; The feeding port was not equipped with a fabric feeder, causing the
material to concentrate and impact the middle of the screen, resulting in local
damage. Strictly control the amount with an electronic belt scale to maintain
the feed rate at 85% -95% of the rated value; Install a curved fabric dispenser
to evenly distribute the material along the width of the screen, with a layer
thickness controlled between 80-120mm to avoid local overload.
Step 3: Optimize buffer protection and equipment maintenance - avoid faults
at the source
Material impact, failure of shock absorption system or insufficient cleaning
can affect equipment stability.
Insufficient buffering protection or abnormal shock absorption: There is no
buffering device installed at the feed inlet, and quartz sand directly impacts
the sieve, resulting in an impact force exceeding the sieve's bearing limit; The
aging of the shock absorber spring (with elastic deformation exceeding 10mm)
makes it unable to absorb vibration energy, resulting in increased vibration of
the screen mesh. Install polyurethane buffer plates at the feed inlet to reduce
material impact force; Replace the high-strength shock-absorbing spring to
ensure that the amplitude of the screen box is stable at 5-8mm, avoiding
resonance damage to the screen mesh.
Insufficient cleaning of the screen surface or mixing of impurities: quartz
sand fine powder binds to the screen mesh, with a pore size blockage rate of
over 30%, resulting in a sudden drop in screening efficiency; Metal blocks,
granite, and other hard objects mixed into the raw materials can collide with
the sieve and cause holes to break. Install an ultrasonic cleaning device (power
1200W) to clean the clogged aperture of the screen in real time; Install a grid
and magnetic separation equipment in front of the vibrating screen to remove
large impurities and metal foreign objects with a particle size exceeding 50mm,
reducing screen damage.
Daily maintenance should pay attention to: checking the tension of the screen
mesh, the operation status of the exciter, and the thickness of the material
layer every day; Calibrate vibration frequency and excitation force weekly, and
clean residual materials on the screen surface; Replace aging shock absorber
springs every month and inspect the welds of the screen box; Perform
non-destructive testing on screening boxes every quarter and reinforce weak
areas. By implementing the above measures, the screening efficiency can be
improved to over 92%, and the service life of the sieve can be extended to over
20 days, ensuring the continuous operation of large-scale quartz sand production
lines. If there are still problems, it is recommended to contact the
manufacturer to optimize the screening box structure and excitation system to
match the needs of large processing capacity quartz sand screening.