The high-efficiency and energy-saving filter press is a key solid-liquid
separation equipment for the tail slurry treatment of large-scale quartz sand
production lines (daily processing capacity ≥ 3000t). It is responsible for
filtering the washed sand tail slurry (solid content 15% -25%) into dry filter
cake (required filter cake moisture content ≤ 18%, filtration efficiency ≥ 80m
³/h), directly determining the tailings recovery and utilization rate and
environmental emission compliance rate. If the moisture content of the filter
cake is high (over 25%) and the filtration efficiency is low (less than 50m
³/h), it will lead to an increase in the transportation cost of the filter cake,
excessive tailwater discharge, and restrict the environmentally friendly and
efficient operation of the production line. Based on the characteristics of fine
particles and high viscosity of quartz sand slurry, a three-step optimization
plan is summarized to quickly improve the operational performance of the filter
press.
Step 1: Optimize the filter plate structure and feeding system to improve
feeding and filtration efficiency
The unreasonable design of the filter plate flow channel and improper feeding
method are the core reasons for low filtration efficiency, and targeted
optimization is needed to adapt to the characteristics of the tail slurry.
Adaptation of filter plate structure and material: ordinary flat filter
plates are selected, which have high resistance to tail slurry flow and slow
filtration speed; The material of the filter plate is ordinary cast iron, which
has poor wear resistance. After more than 6000 hours of use, the surface wears
out and the sealing performance decreases, resulting in leakage of slurry.
Replace the specialized diaphragm filter plate for quartz sand tail slurry,
adopt a "radial flow channel" design, increase the flow area by 30%, and reduce
the feeding resistance; Select high-strength polypropylene filter plates
(wear-resistant and corrosion-resistant), with wear-resistant coatings added to
the surface, extending the service life to over 12000 hours; During
installation, calibrate the parallelism of the filter plate and control the
deviation within 0.5mm to ensure a tight seal.
Parameter regulation of the feeding system: When the feeding pressure is
below 1.2 MPa, the tail slurry cannot quickly permeate and filter, resulting in
low filtration efficiency; Exceeding 1.8MPa can easily cause damage to the
filter cloth and deformation of the filter plate; The fluctuation of the feed
rate exceeds 10%, the load of the filter press is unstable, and the filtration
rhythm is disrupted. Stabilize the pressure at 1.4-1.6MPa by using a variable
frequency feed pump to regulate it; Install an online flow monitoring device to
control the feed rate at 85% -95% of the rated value, avoiding load
fluctuations; Pre treat the tail slurry before feeding, remove coarse particles
with a particle size exceeding 1mm through a cyclone, and reduce filter cloth
clogging.
Step 2: Calibrate the hydraulic press system to improve the dewatering effect
of the filter cake
Insufficient hydraulic pressure, short pressing time, or unstable holding
pressure can lead to high moisture content in the filter cake, requiring precise
control of system parameters.
Optimization of hydraulic pressing parameters: When the pressing pressure is
below 2.5 MPa, the water in the filter cake cannot be fully squeezed out; Above
3.5MPa, it is easy to damage the filter plate and hydraulic components; Pressing
time less than 30 minutes, insufficient dehydration. Stabilize the pressing
pressure at 2.8-3.2MPa through the pressure regulating valve of the hydraulic
station; Adjust the pressing time according to the solid content of the tail
slurry. When the solid content exceeds 20%, extend it to 35-40 minutes, and when
the solid content is ≤ 15%, control it at 30-35 minutes; Activate the pressure
compensation system, which automatically replenishes pressure when the pressure
drops by more than 0.1MPa to ensure stable pressing process.
Hydraulic system maintenance and optimization: Hydraulic oil pollution
exceeds NAS8 level, impurities block the oil circuit, resulting in poor pressure
transmission; Hydraulic pump aging, oil supply pressure fluctuation exceeding
0.2MPa; The wear of the seal causes oil leakage and the pressure cannot be
maintained. Regularly replace anti-wear hydraulic oil and install high-precision
oil filters (filtration accuracy ≤ 10 μ m) to ensure oil cleanliness; Check the
operating status of the hydraulic pump and replace aging components in a timely
manner; Check the integrity of the seals every month, replace worn gaskets, and
avoid oil leakage and pressure relief.
Step 3: Optimize the selection and maintenance of filter cloth to ensure
filtration stability
Mismatched, clogged, or worn filter cloth materials can simultaneously affect
filtration efficiency and cake moisture content, requiring proper selection and
daily maintenance.
Filter cloth selection and adaptation: Choose ordinary polyester filter cloth
with low porosity (<40%), which is easily blocked by fine quartz sand
particles; The mesh size of the filter cloth is inappropriate. When the mesh
size is below 200, fine sand is lost with the filtrate, and when it is above
300, the filtration resistance is too high. Replace the specialized
polypropylene needle punched felt filter cloth for quartz sand (porosity 45%
-50%, mesh size 250-280), with both filtration accuracy and flowability; Select
the surface treatment method based on the characteristics of the tail slurry,
and use a membrane filter cloth when the content of fine particles is high to
enhance the anti clogging ability.
Daily maintenance and cleaning of filter cloth: The filter cloth has been
used for over 80 hours without cleaning, resulting in a blockage rate of over
30% and a sudden drop in filtration efficiency; Incomplete cleaning and residual
mud powder affect the subsequent filtration effect; The filter cloth is damaged
by more than 5mm, resulting in sand leakage and insufficient sand content in the
filter cake. Set the cleaning cycle for the filter cloth, backwash it with
high-pressure water (pressure 3-5 MPa) every 72 hours, and soak it in a weak
alkaline cleaning agent for 30 minutes if necessary before cleaning; Check the
integrity of the filter cloth weekly, repair or replace any damaged parts in a
timely manner to ensure the filtration effect.
Daily maintenance should pay attention to: checking hydraulic pressure,
filter cake moisture content, and filtrate clarity every day; Calibrate the feed
pressure and flow rate weekly, and clean the residual mud and sand in the filter
plate channel; Monthly inspection of filter cloth wear and hydraulic oil
quality; Conduct comprehensive maintenance on the hydraulic system and filter
plates every quarter. By implementing the above measures, the moisture content
of the filter cake can be stabilized below 16%, and the filtration efficiency
can be improved to over 90m ³/h, ensuring the environmentally friendly and
efficient treatment of tailings in large-scale quartz sand production lines. If
there are still problems, it is recommended to contact the manufacturer to
optimize equipment parameters and filter material selection based on the
characteristics of the tail slurry.