The fine sand recycling machine is the core equipment for resource recovery
and environmental protection treatment in large-scale quartz sand production
lines (daily processing capacity ≥ 3000t). It is responsible for recycling fine
sand (particle size 0.1-0.6mm) from sand washing wastewater and tail mortar,
achieving water resource recycling (requiring a fine sand recovery rate of ≥ 90%
and a sand content of ≤ 0.1g/L in the recycled wastewater), directly determining
resource utilization rate, production cost, and environmental compliance rate.
If the recovery rate of fine sand is low (less than 75%) and the sand content in
the wastewater exceeds the standard, it will lead to resource waste,
sedimentation in the sedimentation tank, and even face environmental penalties.
Based on the characteristics of light weight and easy loss with water flow of
quartz sand, a three-step optimization plan is summarized to comprehensively
improve the operational performance of the fine sand recovery machine.
Step 1: Optimize the core configuration of the cyclone and enhance its
ability to separate fine sand
The mismatch of cyclone specifications, imbalance of feed parameters, or
internal structural wear are the core reasons for the low recovery rate of fine
sand, and targeted adaptation to the requirements of fine sand separation is
needed.
Optimization of specifications and materials for cyclones: ordinary
small-diameter cyclones (<200mm) are selected, which have insufficient
processing capacity and incomplete separation of fine sand; There is no
wear-resistant coating on the inner wall, and quartz sand erosion causes
deformation of the cone cavity and deviation of the separation trajectory.
Replace the large-diameter wear-resistant cyclone (diameter 250-300mm), increase
the processing capacity of a single unit to 50-80m ³/h, and adapt to the needs
of large-scale production lines; Spray ceramic wear-resistant coating (thickness
3-5mm) on the inner wall, which increases the wear resistance by more than 4
times and avoids deformation of the cone cavity; Adjust the diameter ratio of
the overflow pipe to the bottom outlet according to the fine sand particle size,
and control it at 1:1.2-1:1.5 to ensure effective separation of fine sand.
Accurate control of feed parameters: feed pressure below 0.15MPa,
insufficient centrifugal force, and ineffective settling of fine sand; Above 0.3
MPa, there is a significant increase in energy consumption and it is easy to
cause wear of the cyclone; The solid content in the feed exceeds 15%, and the
blockage of the slurry affects the separation efficiency. Stabilize the feed
pressure at 0.2-0.25MPa through a variable frequency slurry pump; Install an
online solid content detector and activate the diversion device when the solid
content exceeds 12% to reduce the feed load; Ensure that the flow rate of the
feed pipe is stable at 2.5-3m/s to avoid sedimentation and blockage of the
slurry.
Step 2: Calibrate the dewatering screen parameters to improve the stability
of fine sand dewatering and recovery
Improper amplitude of the dewatering screen, incorrect selection of screen
mesh, or imbalanced vibration parameters can lead to high moisture content and
carryover loss of recovered fine sand, requiring precise regulation and
optimization.
Dehydration screen parameters and screen mesh adaptation: amplitude less than
3mm, insufficient dewatering of fine sand (moisture content exceeding 18%); The
amplitude is greater than 8mm, and the severe vibration of the equipment causes
fine sand splashing; Using ordinary steel wire mesh, the aperture is not
appropriate (<100 mesh is prone to clogging,>150 mesh fine sand is carried
away) and the wear resistance is poor. Stabilize the amplitude at 4-6mm and
control the vibration frequency at 30-35Hz through eccentric block adjustment,
balancing dehydration efficiency and equipment stability; Replace the
polyurethane high-frequency mesh (mesh size 120-140) with a porosity of over
45%, anti clogging and strong wear resistance, and extend the service life to
over 6000 hours; During installation, calibrate the levelness of the screen
surface with a deviation of ≤ 0.5mm/m to avoid the loss of fine sand.
Vibration system and sealing optimization: The phase deviation of the dual
vibration motor exceeds 5 °, the vibration trajectory is disordered, and the
dehydration is uneven; The sealing of the screen surface is poor, and fine sand
is lost through the gaps with the wastewater. Calibrate the phase of the dual
motors to complete synchronization, ensuring that the vibration trajectory is
straight; Install a rubber sealing edge (height 100mm) at the edge of the screen
to prevent fine sand from splashing; Regularly check the fastening status of the
motor fixing bolts, and control the pre tightening torque at 180-220N · m to
prevent loosening during operation.
Step 3: Optimize the water cycle and auxiliary regulation to ensure dual
compliance of recycling and environmental protection
Poor water circulation system, improper adaptation of flocculation agents, or
uneven feeding can exacerbate excessive sand content in wastewater, and system
coordination optimization is necessary.
Water circulation and flow control: The diameter of the return water pipe is
too small or the pipeline is blocked, resulting in poor discharge of wastewater
and sedimentation in the equipment; Flow fluctuations exceeding 10% affect the
stability of cyclone separation. Select large-diameter return water pipes (≥
150mm) and regularly clean the accumulated sand in the pipeline; Install flow
control valves and stabilizing devices to stabilize the circulating water flow
rate at 80-120m ³/h, ensuring that the feeding of the cyclone matches the rhythm
of wastewater discharge; Establish a closed-loop water circulation system to
recycle wastewater directly back to the sand washing machine, increasing water
resource utilization to over 95%.
Flocculation assistance and feed optimization: High mud content wastewater
without flocculant makes it difficult for fine sand to agglomerate and settle;
There is no fabric device at the feed inlet, and the concentrated impact of the
slurry on the cyclone causes uneven separation. Add anionic polyacrylamide
(molecular weight 12-15 million) according to the sludge content of the
wastewater, dilute it to a concentration of 0.1% -0.3%, and evenly add it. The
dosage should be controlled at 3-5g/t to accelerate the agglomeration and
sedimentation of fine sand; Install a spiral feeder at the feeding end to evenly
distribute the slurry into the cyclone and avoid local overload.
Daily maintenance should pay attention to: daily detection of fine sand
recovery rate, recycled sand moisture content, and wastewater sand content;
Clean the sand accumulation inside the cyclone and check the wear of the screen
mesh every week; Calibrate the feed pressure of the cyclone and the vibration
parameters of the dewatering screen every month; Replace the wear-resistant
lining plate of the cyclone and the sealing components of the vibration motor
every quarter. By implementing the above measures, the recovery rate of fine
sand can be increased to over 92%, and the sand content in wastewater can be
stabilized below 0.08g/L, achieving a win-win situation of efficient recovery of
quartz sand resources and environmental compliance, and adapting to the
continuous operation needs of large-scale production lines.